Evaluate:

[tex]\[
x = \frac{-(-2) \pm \sqrt{(-2)^2 - 4(1)(-8)}}{2(1)}
\][/tex]
[tex]\[
x = \frac{2 \pm \text{[?]}}{\text{[]}}
\][/tex]

Enter the number that belongs in the box:

A. 28
B. 6
C. 32
D. [tex][tex]$-2$[/tex][/tex]



Answer :

To solve for [tex]\(x\)[/tex] in the quadratic equation using the quadratic formula, we need to evaluate the expression:

[tex]\[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \][/tex]

Given [tex]\(a = 1\)[/tex], [tex]\(b = -2\)[/tex], and [tex]\(c = -8\)[/tex], the first step is to calculate the discriminant:

[tex]\[ \text{Discriminant} = b^2 - 4ac \][/tex]

Substituting the values of [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(c\)[/tex]:

[tex]\[ \text{Discriminant} = (-2)^2 - 4(1)(-8) \][/tex]

Calculating inside the discriminant:

[tex]\[ \text{Discriminant} = 4 + 32 = 36 \][/tex]

Next, we find the square root of the discriminant:

[tex]\[ \sqrt{36} = 6 \][/tex]

Now, we substitute back into the quadratic formula:

[tex]\[ x = \frac{-(-2) \pm \sqrt{36}}{2(1)} \][/tex]

Simplify the expressions:

[tex]\[ x = \frac{2 \pm 6}{2} \][/tex]

Therefore, the number needed for our problem is 6, because:

[tex]\[ x = \frac{2 \pm [?]}{[]} \][/tex]

We find that [tex]\( \pm ? = 6 \)[/tex].

So, the number that belongs in the green box is:

[tex]\[ \boxed{6} \][/tex]