
Thinking Mathematically (7th Edition)
7th Edition
ISBN: 9780134683713
Author: Robert F. Blitzer
Publisher: PEARSON
expand_more
expand_more
format_list_bulleted
Concept explainers
Textbook Question
Chapter 1, Problem 21RE
In Exercises 21-24, determine each estimate without using a calculator. Then use a calculator to perform the computation necessary to obtain an exact answer. How reasonable is your estimate when compared to the actual answer?
Estimate the total cost of six grocery items if their prices are $8.47, $0.89, $2.79, $0.14, $1.19, and $4.76.
Expert Solution & Answer

Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
charity
savings
Budget for May
travel
food
Peter earned $700 during May. The graph
shows how the money was used.
What fraction was clothes?
O Search
Submit
clothes
leisure
Exercise 11.3 A slope field is given for the equation y' = 4y+4.
(a) Sketch the particular solution that corresponds to y(0) = −2
(b) Find the constant solution
(c) For what initial conditions y(0) is the solution increasing?
(d) For what initial conditions y(0) is the solution decreasing?
(e) Verify these results using only the differential equation y' = 4y+4.
SOLVE ONLY FOR (L) (M) AND (O)
Chapter 1 Solutions
Thinking Mathematically (7th Edition)
Ch. 1.1 - CHECK POINT 1 Find a counterexample to show that...Ch. 1.1 - CHECK POINT 2 Identify a pattern in each list of...Ch. 1.1 - CHECK POINT 3 Identify a pattern in each list of...Ch. 1.1 - CHECK POINT 4 Describe two patterns in this...Ch. 1.1 - CHECK POINT 5 Consider the following procedure:...Ch. 1.1 - The statement 3 + 3 = 6 serves as a/an ________ to...Ch. 1.1 - Arriving at a specific conclusion from one or more...Ch. 1.1 - Arriving at a general conclusion based on...Ch. 1.1 - True or False: A theorem cannot have...Ch. 1.1 - In Exercises 1-8, find a counterexample to show...
Ch. 1.1 - In Exercises 1-8, find a counterexample to show...Ch. 1.1 - In Exercises 1-8, find a counterexample to show...Ch. 1.1 - In Exercises 1-8, find a counterexample to show...Ch. 1.1 - In Exercises 1-8, find a counterexample to show...Ch. 1.1 - In Exercises 1-8, find a counterexample to show...Ch. 1.1 - In Exercises 1-8, find a counterexample to show...Ch. 1.1 - In Exercises 1-8, find a counterexample to show...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, Identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 9-38, identify a pattern in each list...Ch. 1.1 - In Excises 9-38, identify a pattern in each list...Ch. 1.1 - In Exercises 39-42, identify a pattern in each...Ch. 1.1 - In Exercises 39-42, identify a pattern in each...Ch. 1.1 - In Exercises 39-42, identify a pattern in each...Ch. 1.1 - In Exercises 39-42, identify a pattern in each...Ch. 1.1 - Select a number. Multiply the number by 4. Add 8...Ch. 1.1 - Prob. 44ECh. 1.1 - Prob. 45ECh. 1.1 - Prob. 46ECh. 1.1 - In Exercises 47-52, use inductive reasoning to...Ch. 1.1 - In Exercises 47-52, use inductive reasoning to...Ch. 1.1 - In Exercises 47-52, use inductive reasoning to...Ch. 1.1 - In Exercises 47-52, use inductive reasoning to...Ch. 1.1 - In Exercises 47-52, use inductive reasoning to...Ch. 1.1 - In Exercises 47-52, use inductive reasoning to...Ch. 1.1 - In Exercises 53-54, use inductive reasoning to...Ch. 1.1 - In Exercises 53-54, use inductive reasoning to...Ch. 1.1 - Study the pattern in these examples: a 3 # a 4 = a...Ch. 1.1 - Study the pattern in these examples: a 5 * a 3 * a...Ch. 1.1 - In Exercises 57-60, identify the reasoning...Ch. 1.1 - In Exercises 57-60, identify the reasoning...Ch. 1.1 - Prob. 59ECh. 1.1 - In Exercises 57-60, identify the reasoning...Ch. 1.1 - The ancient Greeks studies figurate numbers, so...Ch. 1.1 - The triangular arrangement of numbers shown below...Ch. 1.1 - Writing about mathematics will help you to learn...Ch. 1.1 - Describe what is meant by deductive reasoning....Ch. 1.1 - Give an example of a decision that you made...Ch. 1.1 - Make Sense? In Exercises 66-69, determine whether...Ch. 1.1 - Make sense? In Exercises 66-69, determine whether...Ch. 1.1 - I used the data shown in the bar graph, which...Ch. 1.1 - I used the data shown in the bar graph for...Ch. 1.1 - If ( 6 − 2 ) 2 = 36 − 24 + 4 and ( 8 − 5 ) 2 = 64...Ch. 1.1 - 71. The rectangle shows an array of nine numbers...Ch. 1.1 - Write a list of numbers that has two patterns so...Ch. 1.1 - a. Repeat the following procedure with at least...Ch. 1.1 - a. Use a calculator to find 6 × 6 , 66 × 66 , 666...Ch. 1.1 - 75. a. Use a calculator to find , and .
b....Ch. 1.1 - Stereotyping refers to classifying people, places,...Ch. 1.2 - CHECK POINT 1 Round world population...Ch. 1.2 - CHECK POINT 2 Round 3.141592, the first seven...Ch. 1.2 - CHECK POINT 3 You and a friend ate lunch at Ye...Ch. 1.2 - CHECK POINT 4 A Landscape architect who works full...Ch. 1.2 -
Source Natural Home and Garden
CHECK POINT 5...Ch. 1.2 - CHECK POINT 6 Use the date for women in Figure 1.5...Ch. 1.2 - CHECK POINT 7 Use the line graph in Figure 1.7 at...Ch. 1.2 - CHECK POINT 8 The bar graph in Figure 1.9 on the...Ch. 1.2 - The process of arriving at an approximate answer...Ch. 1.2 - Fill in each blank so that the resulting statement...Ch. 1.2 - Fill in each blank so that the resulting statement...Ch. 1.2 - Fill in each blank so that resulting statement is...Ch. 1.2 - Prob. 5CVCCh. 1.2 - Fill in each blank so that the resulting statement...Ch. 1.2 - The bar graph gives the populations of the ten...Ch. 1.2 - The bar graph gives the 2011 populations of the...Ch. 1.2 - In Exercises 3-8, use this approximation to round...Ch. 1.2 - In Exercises 3-8, use this approximation to round...Ch. 1.2 - In Exercises 3-8, use this approximation to round...Ch. 1.2 - In Exercises 3-8, use this approximation to round...Ch. 1.2 - In Exercises 3-8, use this approximation to round...Ch. 1.2 - In Exercises 3-8, use this approximation to round...Ch. 1.2 - In Exercises 9-34, because different rounding...Ch. 1.2 - In Exercises 9-34, because different rounding...Ch. 1.2 - In Exercises 9-34, because different rounding...Ch. 1.2 - In Exercises 9-34, because different rounding...Ch. 1.2 - In Exercises 9-34, because different rounding...Ch. 1.2 - In Exercises 9-34, because different rounding...Ch. 1.2 - In Exercises 9-34, because different rounding...Ch. 1.2 - In Exercises 9-34, because different rounding...Ch. 1.2 - In Exercises 9-34, because different rounding...Ch. 1.2 - In Exercises 9-34, because different rounding...Ch. 1.2 - In Exercises 9-34, because different rounding...Ch. 1.2 - In Exercises 9-34, because different rounding...Ch. 1.2 - In Exercises 9-34, because different rounding...Ch. 1.2 - In Exercises 9-34, because different rounding...Ch. 1.2 - In Exercises 23-34, determine each estimate...Ch. 1.2 - In Exercises 23-34, determine each estimate...Ch. 1.2 - In Exercises 23-34, determine each estimate...Ch. 1.2 - In Exercises 23-34, determine each estimate...Ch. 1.2 - In Exercises 23-34, determine each estimate...Ch. 1.2 - In Exercises 23-34, determine each estimate...Ch. 1.2 - In Exercises 23-34, determine each estimate...Ch. 1.2 - In Exercises 23-34, determine each estimate...Ch. 1.2 - In Exercises 23-34, determine each estimate...Ch. 1.2 - In Exercises 23-34, determine each estimate...Ch. 1.2 - In Exercises 23-34, determine each estimate...Ch. 1.2 - The average life expectancy in Mozambique is 40.3...Ch. 1.2 - In Exercises 35-36, obtain an estimate for each...Ch. 1.2 - In Exercises 35-36, obtain an estimate for each...Ch. 1.2 - Ten people ordered calculators. The least...Ch. 1.2 - Ten people ordered calculators. The least...Ch. 1.2 - Travelling at an average rate of between 60 and 70...Ch. 1.2 - Prob. 40ECh. 1.2 - 41. Imagine that you counted 60 numbers per minute...Ch. 1.2 - Prob. 42ECh. 1.2 - 43. Without using a calculator, estimate the...Ch. 1.2 - Without using a calculator, estimate the number of...Ch. 1.2 - An online test of English spelling looked at how...Ch. 1.2 - An online test of English spelling looked at how...Ch. 1.2 - The percentage of U.S. college freshmen claiming...Ch. 1.2 - The percentage of U.S. college freshmen claiming...Ch. 1.2 - With aging, body fat increases and muscle mass...Ch. 1.2 - With aging, body fat increases and muscle mass...Ch. 1.2 - There is a strong scientific consensus that human...Ch. 1.2 - Prob. 52ECh. 1.2 - Prob. 53ECh. 1.2 - Prob. 54ECh. 1.2 - Explain how to round 14.26841 to the nearest...Ch. 1.2 - Prob. 56ECh. 1.2 - 57. In this era of calculators and computers, why...Ch. 1.2 - Prob. 58ECh. 1.2 - Prob. 59ECh. 1.2 - Prob. 60ECh. 1.2 - Prob. 61ECh. 1.2 - College students are graduating with the highest...Ch. 1.2 - Explain how to use the estimate from Exercise 62...Ch. 1.2 - Prob. 64ECh. 1.2 - 65. A forecaster at the National Hurricane Center...Ch. 1.2 - Prob. 66ECh. 1.2 - Prob. 67ECh. 1.2 - Prob. 68ECh. 1.2 - Prob. 69ECh. 1.2 - Prob. 70ECh. 1.2 - In Exercises 71-74, match the story with the...Ch. 1.2 - In Exercises 71-74, match the story with the...Ch. 1.2 - In Exercises 71-74, match the story with the...Ch. 1.2 - In Exercises 71-74, match the story with the...Ch. 1.2 - 75. American children ages 2 to 17 spend 19 hours...Ch. 1.2 - Prob. 76ECh. 1.2 - 77. Group members should devise an estimation...Ch. 1.2 - Group members should begin by consulting an...Ch. 1.3 - CHECK POINT 1 Which necessary piece of information...Ch. 1.3 - CHECK POINT 2 Solve the following problem. If the...Ch. 1.3 - CHECK POINT 3 By paying $350 cash up front and the...Ch. 1.3 - CHECK POINT 4 Suppose you are an engineer...Ch. 1.3 - CHECK POINT 5 Your “lecture wardrobe” is rather...Ch. 1.3 - CHECK POINT 6 As in Example 6, a sales director...Ch. 1.3 - The first step in problem solving is to read the...Ch. 1.3 - 2. The second step in problem solving is to ____...Ch. 1.3 - True or False: Polya’s four steps in problem...Ch. 1.3 - True or False: When making a choice between...Ch. 1.3 - In Exercises 1-4, what necessary piece of...Ch. 1.3 - In Exercises 1-4, what necessary piece of...Ch. 1.3 - In Exercises 1-4, what necessary piece of...Ch. 1.3 - In Exercises 1-4, what necessary piece of...Ch. 1.3 - In Exercises 5-8, one more piece of information is...Ch. 1.3 - In Exercises 5-8, one more piece of information is...Ch. 1.3 - In Exercises 5-8, one more piece of information is...Ch. 1.3 - In Exercises 5-8, one more piece of information is...Ch. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Use the following movie-rental options to solve...Ch. 1.3 - Use the following movie-rental options to solve...Ch. 1.3 - Acetaminophen is in many non-prescription...Ch. 1.3 - Acetaminophen is in many non-prescription...Ch. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Prob. 18ECh. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Prob. 20ECh. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Prob. 24ECh. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Prob. 27ECh. 1.3 - Prob. 28ECh. 1.3 - Prob. 29ECh. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Prob. 34ECh. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Prob. 36ECh. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Prob. 38ECh. 1.3 - Prob. 39ECh. 1.3 - Prob. 40ECh. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Prob. 42ECh. 1.3 - Use Polya’s four-step method in problem solving to...Ch. 1.3 - Prob. 44ECh. 1.3 - Prob. 45ECh. 1.3 - Prob. 46ECh. 1.3 - The map shows five western states. Trace a route...Ch. 1.3 - The layout of a city with land masses and bridges...Ch. 1.3 - Prob. 49ECh. 1.3 - The figure represents a map of 13 countries. If...Ch. 1.3 - Prob. 51ECh. 1.3 - Prob. 52ECh. 1.3 - As in Sudoku, fill in the missing numbers in the...Ch. 1.3 - The missing numbers in the 4-by-4 array are...Ch. 1.3 - Prob. 55ECh. 1.3 - Prob. 56ECh. 1.3 - Prob. 57ECh. 1.3 - In Exercises 52-54, explain the plan needed to...Ch. 1.3 - Prob. 59ECh. 1.3 - Make Sense? In Exercises 56-59, determine whether...Ch. 1.3 - Make Sense? In Exercises 56-59, determine whether...Ch. 1.3 - Make Sense? In Exercises 56-59, determine whether...Ch. 1.3 - Make Sense? In Exercises 56-59, determine whether...Ch. 1.3 - 60. Gym lockers are to be numbered from 1 through...Ch. 1.3 - Prob. 65ECh. 1.3 - Prob. 66ECh. 1.3 - 63. One person tells the truth on Monday, Tuesday,...Ch. 1.3 - Prob. 68ECh. 1.3 - 65. As in Sudoku, fill in the missing numbers...Ch. 1.3 - Prob. 70ECh. 1.3 - Prob. 71ECh. 1.3 - Prob. 72ECh. 1.3 - Prob. 73ECh. 1.3 - Prob. 74ECh. 1.3 - Prob. 75ECh. 1.3 - Prob. 76ECh. 1.3 - Prob. 77ECh. 1.3 - Prob. 78ECh. 1.3 - Group members should describe a problem in need of...Ch. 1 - 1. Which reasoning process is shown in the...Ch. 1 - 2. Which reasoning process is shown in the...Ch. 1 - In Exercises 3-10, identify a pattern in each list...Ch. 1 - Prob. 4RECh. 1 - In Exercises 3-10, identify a pattern in each list...Ch. 1 - Prob. 6RECh. 1 - Prob. 7RECh. 1 - In Exercises 3-10, identify a pattern in each list...Ch. 1 - Prob. 9RECh. 1 - Prob. 10RECh. 1 - Identify a pattern in the following sequence of...Ch. 1 - In Exercises 12-13, use inductive reasoning to...Ch. 1 - Prob. 13RECh. 1 - Consider the following procedure: Select a number....Ch. 1 - Prob. 15RECh. 1 - Prob. 16RECh. 1 - In Exercises 17-20, obtain an estimate for each...Ch. 1 - In Exercises 17-20, obtain an estimate for each...Ch. 1 - Prob. 19RECh. 1 - Prob. 20RECh. 1 - In Exercises 21-24, determine each estimate...Ch. 1 - Prob. 22RECh. 1 - In Exercises 21-24, determine each estimate...Ch. 1 - In Exercises 21-24, determine each estimate...Ch. 1 - A small private school employs 10 teachers with...Ch. 1 - Prob. 26RECh. 1 - Prob. 27RECh. 1 - 28. The bar graph shows the percentage of people...Ch. 1 - Prob. 29RECh. 1 - The bar graph shows the population of the Unites...Ch. 1 - Prob. 31RECh. 1 - Prob. 32RECh. 1 - Use the four-step method in problem solving to...Ch. 1 - Prob. 34RECh. 1 - Use the four-step method in problem solving to...Ch. 1 - Prob. 36RECh. 1 - Prob. 37RECh. 1 - Use the four-step method in problem solving to...Ch. 1 - Use the four-step method in problem solving to...Ch. 1 - Prob. 1TCh. 1 - Prob. 2TCh. 1 - Prob. 3TCh. 1 - In Exercises 3-6, find the next number,...Ch. 1 - In Exercises 3-6, find the next number,...Ch. 1 - Prob. 6TCh. 1 - Prob. 7TCh. 1 - 8. Round 3,279,425 to the nearest hundred...Ch. 1 - Prob. 9TCh. 1 - Prob. 10TCh. 1 - Prob. 11TCh. 1 - Prob. 12TCh. 1 - Prob. 13TCh. 1 - Prob. 14TCh. 1 - Prob. 15TCh. 1 - Prob. 16TCh. 1 - 17. The cost of renting a boat from Estes Rental...Ch. 1 - Prob. 18TCh. 1 - Prob. 19TCh. 1 - Prob. 20T
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, subject and related others by exploring similar questions and additional content below.Similar questions
- Aphids are discovered in a pear orchard. The Department of Agriculture has determined that the population of aphids t hours after the orchard has been sprayed is approximated by N(t)=1800−3tln(0.17t)+t where 0<t≤1000. Step 1 of 2: Find N(63). Round to the nearest whole number.arrow_forward1. A telegraph can transmit two different signals: a dot and a dash. We want to encode the 26 letters of the English alphabet and the ten digits 0, 1, 2, . . . , 9 using sequences of these two symbols. What is the smallest integer n such that we can encode all these letters and digits with sequences of length at most n and length at least 1?arrow_forwardUse the graph of y = f(x) to answer the following. 3- 2 -4 -2 -1 1 2 3 4 -1 2 m -3- + (d) Find all x for which f(x) = -2. If there is more than one value, separate them with commas or write your answer in interval notation, if necessary. Select "None", if applicable. Value(s) of x for which f(x)=-2: | (0,0) (0,0) (0,0) (0,0) 0,0... -00 None (h) Determine the range of f. The range is (0,0) Garrow_forward
- File Preview A gardener has ten different potted plants, and they are spraying the plants with doses of Tertizers. Plants can receive zero or more doses in a session. In the following, we count each possible number of doses the ten plants can receive (the order of spraying in a session does not matter). (a) How many ways are there if there were twelve total doses of a single type of fertilizer? (b) How many ways are there if there are six total doses of a single type of fertilizer, each plant receives no more than one dose? (c) How many ways are there if is was one dose of each of six types of fertilizers? (d) How many ways are there if there are four doses of fertilizer #1 and eight doses of fertilizer #2? (e) How many ways are there if there are four doses of fertilizer #1 and eight doses of fertilizer #2, and each plant receives no more than one dose of fertilizer #1? (f) How many ways are there to do two sessions of spraying, where each plant receives at most two doses total?arrow_forward3. [-/3 Points] DETAILS MY NOTES SCALCET8 7.4.032. ASK YOUR TEACHER PRACTICE ANOTHER Evaluate the integral. X + 4x + 13 Need Help? Read It SUBMIT ANSWER dxarrow_forwardEvaluate the limit, and show your answer to 4 decimals if necessary. Iz² - y²z lim (x,y,z)>(9,6,4) xyz 1 -arrow_forward
- show workarrow_forward2011 listing by carmax of the ages and prices of various corollas in a ceratin regionarrow_forwardس 11/ أ . اذا كانت 1 + x) = 2 x 3 + 2 x 2 + x) هي متعددة حدود محسوبة باستخدام طريقة الفروقات المنتهية (finite differences) من جدول البيانات التالي للدالة (f(x . احسب قيمة . ( 2 درجة ) xi k=0 k=1 k=2 k=3 0 3 1 2 2 2 3 αarrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- Holt Mcdougal Larson Pre-algebra: Student Edition...AlgebraISBN:9780547587776Author:HOLT MCDOUGALPublisher:HOLT MCDOUGALGlencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw Hill

Holt Mcdougal Larson Pre-algebra: Student Edition...
Algebra
ISBN:9780547587776
Author:HOLT MCDOUGAL
Publisher:HOLT MCDOUGAL

Glencoe Algebra 1, Student Edition, 9780079039897...
Algebra
ISBN:9780079039897
Author:Carter
Publisher:McGraw Hill
Use of ALGEBRA in REAL LIFE; Author: Fast and Easy Maths !;https://www.youtube.com/watch?v=9_PbWFpvkDc;License: Standard YouTube License, CC-BY
Compound Interest Formula Explained, Investment, Monthly & Continuously, Word Problems, Algebra; Author: The Organic Chemistry Tutor;https://www.youtube.com/watch?v=P182Abv3fOk;License: Standard YouTube License, CC-BY
Applications of Algebra (Digit, Age, Work, Clock, Mixture and Rate Problems); Author: EngineerProf PH;https://www.youtube.com/watch?v=Y8aJ_wYCS2g;License: Standard YouTube License, CC-BY