Select the correct answer.

The graph of [tex]f(x)=7^x[/tex] is stretched vertically by a factor of five. Which of the following is the equation of the new graph, [tex]g(x)[/tex]?

A. [tex]g(x)=5\left(7^x\right)[/tex]
B. [tex]g(x)=5^{(7 x)}[/tex]
C. [tex]g(x)=7\left(5^x\right)[/tex]
D. [tex]g(x)=7^{(5 x)}[/tex]



Answer :

To determine the equation of the new graph [tex]\( g(x) \)[/tex] after applying a vertical stretch by a factor of 5 to the original function [tex]\( f(x) = 7^x \)[/tex], follow these steps:

1. Understanding the original function [tex]\( f(x) \)[/tex]:
The given function is [tex]\( f(x) = 7^x \)[/tex].

2. Applying a vertical stretch:
A vertical stretch by a factor of [tex]\( a \)[/tex] transforms the function [tex]\( f(x) \)[/tex] to [tex]\( a \cdot f(x) \)[/tex]. In this case, the stretch factor is 5.

3. Forming the new function [tex]\( g(x) \)[/tex]:
To apply a vertical stretch by a factor of 5 to [tex]\( f(x) = 7^x \)[/tex], multiply the entire function [tex]\( 7^x \)[/tex] by 5.

Therefore, the new function [tex]\( g(x) \)[/tex] is:

[tex]\[ g(x) = 5 \cdot 7^x \][/tex]

Let's now identify the correct option:

A. [tex]\( g(x) = 5 \left( 7^x \right) \)[/tex] is correct.

B. [tex]\( g(x) = 5^{(7 x)} \)[/tex] is incorrect because this represents an exponential function with base 5 raised to the power of [tex]\( 7x \)[/tex].

C. [tex]\( g(x) = 7 \left( 5^x \right) \)[/tex] is incorrect because this represents the function with base 5 raised to the power of [tex]\( x \)[/tex], then multiplied by 7.

D. [tex]\( g(x) = 7^{(5 x)} \)[/tex] is incorrect because this represents an exponential function with base 7 raised to the power of [tex]\( 5x \)[/tex].

The correct answer is thus:

[tex]\[ \boxed{A} \][/tex]