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The first steps in writing [tex]\( f(x) = 3x^2 - 24x + 10 \)[/tex] in vertex form are shown:

[tex]\[
\begin{array}{l}
f(x) = 3(x^2 - 8x) + 10 \\
\left(\frac{-8}{2}\right)^2 = 16
\end{array}
\][/tex]

What is the function written in vertex form?

A. [tex]\( f(x) = 3(x + 4)^2 - 6 \)[/tex]

B. [tex]\( f(x) = 3(x + 4)^2 - 38 \)[/tex]

C. [tex]\( f(x) = 3(x - 4)^2 - 6 \)[/tex]

D. [tex]\( f(x) = 3(x - 4)^2 - 38 \)[/tex]


Sagot :

To write the quadratic function [tex]\( f(x) = 3x^2 - 24x + 10 \)[/tex] in vertex form, let's follow through the steps:

1. Factor out the coefficient of [tex]\( x^2 \)[/tex] from the first two terms:
[tex]\[ f(x) = 3(x^2 - 8x) + 10 \][/tex]

2. Complete the square inside the parentheses. To do this, we use the formula [tex]\(\left( \frac{b}{2} \right)^2\)[/tex], where [tex]\( b \)[/tex] is the coefficient of [tex]\( x \)[/tex] in the expression [tex]\( x^2 - 8x \)[/tex]. Here, [tex]\( b = -8 \)[/tex], so:
[tex]\[ \left( \frac{-8}{2} \right)^2 = (-4)^2 = 16 \][/tex]

3. Add and subtract this square inside the parentheses:
[tex]\[ f(x) = 3(x^2 - 8x + 16 - 16) + 10 \][/tex]
This can be written as:
[tex]\[ f(x) = 3((x^2 - 8x + 16) - 16) + 10 \][/tex]

4. Rewriting the perfect square trinomial as a square of a binomial:
[tex]\[ f(x) = 3((x - 4)^2 - 16) + 10 \][/tex]

5. Distribute the 3 across the terms inside the parentheses:
[tex]\[ f(x) = 3(x - 4)^2 - 3 \times 16 + 10 \][/tex]
Simplifying further:
[tex]\[ f(x) = 3(x - 4)^2 - 48 + 10 \][/tex]

6. Combine the constants:
[tex]\[ f(x) = 3(x - 4)^2 - 38 \][/tex]

Therefore, the function written in vertex form is:
[tex]\[ f(x) = 3(x - 4)^2 - 38 \][/tex]

So, the correct choice is [tex]\( \boxed{f(x) = 3(x - 4)^2 - 38} \)[/tex].