Which function is the result of vertically stretching [tex]$f(x)=x^2-7$[/tex] by a factor of 2 and translating it downward 5 units?

A) [tex]$y=2x^2-2$[/tex]
B) [tex][tex]$y=2x^2-12$[/tex][/tex]
C) [tex]$y=2x^2-5$[/tex]
D) [tex]$y=x^2-12$[/tex]



Answer :

To determine the resulting function when the function [tex]\( f(x) = x^2 - 7 \)[/tex] is vertically stretched by a factor of 2 and then translated downward by 5 units, let's go through each transformation step by step.

1. Vertically stretch by a factor of 2:
When a function [tex]\( f(x) \)[/tex] is vertically stretched by a factor of 2, every y-value is multiplied by 2. So, the new function after vertical stretching is:
[tex]\[ y = 2 \cdot (x^2 - 7) \][/tex]
Simplifying this expression:
[tex]\[ y = 2x^2 - 14 \][/tex]

2. Translate downward by 5 units:
When a function is translated downward by 5 units, we subtract 5 from every y-value. So, the new function after this translation is:
[tex]\[ y = 2x^2 - 14 - 5 \][/tex]
Simplifying this expression:
[tex]\[ y = 2x^2 - 19 \][/tex]

Having performed both transformations, the resulting function is:
[tex]\[ y = 2x^2 - 19 \][/tex]

Now, let's compare this result with the given options:

A) [tex]\( y = 2x^2 - 2 \)[/tex]
B) [tex]\( y = 2x^2 - 12 \)[/tex]
C) [tex]\( y = 2x^2 - 5 \)[/tex]
D) [tex]\( y = x^2 - 12 \)[/tex]

None of the provided options match the result [tex]\( y = 2x^2 - 19 \)[/tex]. Therefore, the answer is that none of the given options are correct.

Following through the entire process step-by-step, none of the provided options are the correct transformed function. Thus, the correct answer among the given choices is:

[tex]\[ \boxed{-1} \][/tex]