Which of the following functions translates the graph of the parent function [tex]f(x) = x^2[/tex] horizontally left 8 units? Illustrate why your choice works.

A. [tex]h(x) = x^2 + 8[/tex]
B. [tex]h(x) = (x - 8)^2[/tex]
C. [tex]h(x) = x^2 - 8[/tex]
D. [tex]h(x) = (x + 8)^2[/tex]



Answer :

To determine which function translates the graph of the parent function [tex]\( f(x) = x^2 \)[/tex] horizontally to the left by 8 units, we need to understand how horizontal translations work.

### Horizontal Translations
For a given function [tex]\( f(x) \)[/tex]:
- To translate it to the left by [tex]\( h \)[/tex] units, you transform [tex]\( f(x) \)[/tex] to [tex]\( f(x + h) \)[/tex].
- To translate it to the right by [tex]\( h \)[/tex] units, you transform [tex]\( f(x) \)[/tex] to [tex]\( f(x - h) \)[/tex].

Given that we want to translate the function [tex]\( f(x) = x^2 \)[/tex] to the left by 8 units, we replace [tex]\( x \)[/tex] with [tex]\( x + 8 \)[/tex]:

[tex]\[ h(x) = (x + 8)^2 \][/tex]

Now, let's verify the given options against our transformation:

- Option A: [tex]\( h(x) = x^2 + 8 \)[/tex]

This shifts the graph vertically up by 8 units, not horizontally. So, this is incorrect.

- Option B: [tex]\( h(x) = (x - 8)^2 \)[/tex]

This shifts the graph horizontally to the right by 8 units, not to the left. So, this is also incorrect.

- Option C: [tex]\( h(x) = x^2 - 8 \)[/tex]

This shifts the graph vertically down by 8 units, not horizontally. Thus, this is incorrect as well.

- Option D: [tex]\( h(x) = (x + 8)^2 \)[/tex]

This shifts the graph horizontally to the left by 8 units, which is exactly what we need.

Thus, the correct option is:

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