Chapter 7.1, Problem 71E

The ordered pairs below give the intensities y in microwatts per square centimeter of the light measured by a light probe located x centimeters from a light source.A model that approximates the data is y = 171.33/x2. (a) Use a graphing utility to plot the data points and the model in the same viewing window. (b) Use the model to approximate the light intensity 25 centimeters from the light source.

Q42) (a) The temperature gauge of a car is giving an overheating warning and the car is stopped. At time i minutes, the temperature Tof the liquid in the radiator decreases according to the equation dT = -k(T – 35), where k is a positive constant. The initial temperature of the dt liquid in the radiator is 95°C and it cools to 70°C after 10 minutes. đT =-k(T – 35) dt (1) Show that T = 35+ Ae¨ is a solution of (ii) Find the value of A. (iii) Find the value of k , correct to 3 decimal places. (iv) How long will it take for the temperature of the radiator to cool to 40°C? Give your answer correct to the nearest minute.

FLUENCY 1. Which of the following is a quadratic function? (1) y=3x-2 (3) y=x² - 4 (2) y=x' +2x² -1 (4) y = 6(2)"