Question

describe how you could use a graphing calculator to estimate the value of x when f(x) = 8(1.25)^x equals 15. choose the correct answer below a. enter the function f(x) = 8(1.25)^x on the y = screen, display the corresponding table, and find the value of x where y = 15 b. enter the function f(x) = 8(1.25)^x - 15 on the y = screen, display the corresponding table, and find the value of x where y = 15 c. enter the function f(x) = 8(1.25)^x - 15 on the y = screen, display the corresponding table, and find the value of y where x = 15 d. enter the function f(x) = 8(1.25)^x on the y = screen, display the corresponding table, and find the value of y where x = 15

Explanation:

We need to find \( x \) when \( f(x) = 8(1.25)^x=15 \). So we should enter the function \( f(x) = 8(1.25)^x \) (which is \( y = 8(1.25)^x \)) into the graphing calculator, display the table, and then find the \( x \)-value where \( y = 15 \). Option A describes this correctly. Option B and C have a subtraction of 15 which is incorrect as our equation is \( 8(1.25)^x = 15 \), not \( 8(1.25)^x-15 = 15 \) or similar. Option D finds \( y \) when \( x = 15 \), which is not what we need.

Answer:

A. Enter the function \( f(x) = 8(1.25)^x \) on the \( Y = \) screen, display the corresponding table, and find the value of \( x \) where \( y = 15 \)