If you vertically stretch the quadratic parent function [tex]\( F(x) = x^2 \)[/tex] by multiplying by 7, what is the equation of the new function?

A. [tex]\( G(x) = (x + 7)^2 \)[/tex]

B. [tex]\( G(x) = 7x^2 \)[/tex]

C. [tex]\( G(x) = (7x)^2 \)[/tex]

D. [tex]\( G(x) = x^2 - 7 \)[/tex]



Answer :

To determine the equation of the new function when vertically stretching the quadratic parent function [tex]\( F(x) = x^2 \)[/tex] by multiplying by 7, follow these steps:

1. Identify the parent function: [tex]\( F(x) = x^2 \)[/tex].
2. Understand what a vertical stretch means. When you vertically stretch a function by a factor, you multiply the entire function by that factor.

Given that the vertical stretch factor is 7, we need to multiply the parent function [tex]\( F(x) \)[/tex] by 7:

[tex]\[ F(x) \rightarrow G(x) = 7 \cdot F(x) \][/tex]

Since [tex]\( F(x) = x^2 \)[/tex], the new function will be:

[tex]\[ G(x) = 7 \cdot x^2 \][/tex]

This is a direct vertical stretch of the parent function by a factor of 7.

Therefore, the equation of the new function is [tex]\( G(x) = 7x^2 \)[/tex].

Matching this with the given options, we see that:
- Option A: [tex]\( G(x) = (x+7)^2 \)[/tex] is incorrect, as it represents a horizontal shift, not a vertical stretch.
- Option B: [tex]\( G(x) = 7x^2 \)[/tex] is correct, as explained above.
- Option C: [tex]\( G(x) = (7x)^2 \)[/tex] represents a horizontal stretch, not a vertical stretch.
- Option D: [tex]\( G(x) = x^2 - 7 \)[/tex] represents a vertical shift downwards.

Thus, the correct answer is:

[tex]\[ B. \, G(x) = 7x^2 \][/tex]