
Concept explainers
In Exercises 6—10, we consider the phenomenon of radioactive decay which, from experimentation, we know behaves according to the law:
The rate at which a quantity of a radioactive isotope decays is proportional to the amount of the isotope present. The proportionality constant depends only on which radioactive isotope is used.
9. Engineers and scientists often measure the rate of decay of an exponentially decaying quantity using its time constant. The time constant
(a) How are the time constant
(b) Express the time constant in terms of the half-life.
(c) What are the time constants for Carbon 14 and Iodine 131?
(d) Given an exponentially decaying quantity r(t) with initial value r0= r(0), show that its time constant is the time at which the tangent line to the graph of r(t)/r0at (0, l) crosses the t-axis. [Hint: Start by sketching the graph of r(t)/r0and the line tangent to the graph at (0, 1).]
(e) It is often said that an exponentially decaying quantity reaches its steady state in five time constants, that is, at t =5

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Chapter 1 Solutions
Differential Equations (with DE Tools Printed Access Card)
- (b) 4) Find an equation to fit each of the following graphs: (a) 20 20 18 16 14 12 10 8 6 4 2 24 22 20 18 16 14 12 10 8 16 A 2 -3 -2 -1-0 2 3 4. -1 0 1 2 3. -2 -2arrow_forward3) Which of the following are equivalent to 3? (There may be more than one that is equivalent!) -1 (a) (9)¯¹ 3. (b) (-3)-1 (c) (-3) -1 (d) -(¯3) (e) 11 3-1 (f) 3-4arrow_forwardY- ___b=_____ (X- )arrow_forward
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- 1. A consumer group claims that the mean annual consumption of cheddar cheese by a person in the United States is at most 10.3 pounds. A random sample of 100 people in the United States has a mean annual cheddar cheese consumption of 9.9 pounds. Assume the population standard deviation is 2.1 pounds. At a = 0.05, can you reject the claim? (Adapted from U.S. Department of Agriculture) State the hypotheses: Calculate the test statistic: Calculate the P-value: Conclusion (reject or fail to reject Ho): 2. The CEO of a manufacturing facility claims that the mean workday of the company's assembly line employees is less than 8.5 hours. A random sample of 25 of the company's assembly line employees has a mean workday of 8.2 hours. Assume the population standard deviation is 0.5 hour and the population is normally distributed. At a = 0.01, test the CEO's claim. State the hypotheses: Calculate the test statistic: Calculate the P-value: Conclusion (reject or fail to reject Ho): Statisticsarrow_forwardPage < 1 of 2 - ZOOM + 1) a) Find a matrix P such that PT AP orthogonally diagonalizes the following matrix A. = [{² 1] A = b) Verify that PT AP gives the correct diagonal form. 2 01 -2 3 2) Given the following matrices A = -1 0 1] an and B = 0 1 -3 2 find the following matrices: a) (AB) b) (BA)T 3) Find the inverse of the following matrix A using Gauss-Jordan elimination or adjoint of the matrix and check the correctness of your answer (Hint: AA¯¹ = I). [1 1 1 A = 3 5 4 L3 6 5 4) Solve the following system of linear equations using any one of Cramer's Rule, Gaussian Elimination, Gauss-Jordan Elimination or Inverse Matrix methods and check the correctness of your answer. 4x-y-z=1 2x + 2y + 3z = 10 5x-2y-2z = -1 5) a) Describe the zero vector and the additive inverse of a vector in the vector space, M3,3. b) Determine if the following set S is a subspace of M3,3 with the standard operations. Show all appropriate supporting work.arrow_forwardFind the Laplace Transform of the function to express it in frequency domain form.arrow_forward
- Please draw a graph that represents the system of equations f(x) = x2 + 2x + 2 and g(x) = –x2 + 2x + 4?arrow_forwardGiven the following system of equations and its graph below, what can be determined about the slopes and y-intercepts of the system of equations? 7 y 6 5 4 3 2 -6-5-4-3-2-1 1+ -2 1 2 3 4 5 6 x + 2y = 8 2x + 4y = 12 The slopes are different, and the y-intercepts are different. The slopes are different, and the y-intercepts are the same. The slopes are the same, and the y-intercepts are different. O The slopes are the same, and the y-intercepts are the same.arrow_forwardChoose the function to match the graph. -2- 0 -7 -8 -9 --10- |--11- -12- f(x) = log x + 5 f(x) = log x - 5 f(x) = log (x+5) f(x) = log (x-5) 9 10 11 12 13 14arrow_forward
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