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Montiah solved a quadratic equation. Her work is shown below. In which step did Montiah make an error?

[tex]\[
\begin{array}{ll}
3(x+8)^2 + 8 = 83 & \\
3(x+8)^2 = 75 & \text{Step 1} \\
(x+8)^2 = 25 & \text{Step 2} \\
x+8 = \pm 5 & \text{Step 3} \\
x = -3 \text{ or } x = -13 & \text{Step 4}
\end{array}
\][/tex]

A. Step 1

B. Step 2

C. Step 3

D. Step 4


Sagot :

Let's carefully go through the steps Montiah performed to solve the quadratic equation [tex]\(3(x+8)^2 + 8 = 83\)[/tex].

1. Starting from the given equation [tex]\(3(x+8)^2 + 8 = 83\)[/tex]:

[tex]\[ 3(x+8)^2 + 8 = 83 \][/tex]

First, subtract 8 from both sides to isolate the quadratic term:

[tex]\[ 3(x+8)^2 + 8 - 8 = 83 - 8 \][/tex]

[tex]\[ 3(x+8)^2 = 75 \][/tex]

Step 1 is correct.

2. Next, divide both sides by 3 to solve for [tex]\((x+8)^2\)[/tex]:

[tex]\[ \frac{3(x+8)^2}{3} = \frac{75}{3} \][/tex]

[tex]\[ (x+8)^2 = 25 \][/tex]

In Step 2, Montiah has made an error. Instead of [tex]\((x+8)^2 = 25\)[/tex], she wrote [tex]\((x+8)^2 = 225\)[/tex].

3. If [tex]\((x+8)^2 = 25\)[/tex], to solve for [tex]\(x\)[/tex], take the square root of both sides:

[tex]\[ x+8 = \pm 5 \][/tex]

Step 3 is correct according to the corrected version of Step 2.

4. Solving [tex]\(x+8 = \pm 5\)[/tex]:

[tex]\[ x+8 = 5 \quad \text{or} \quad x+8 = -5 \][/tex]

[tex]\[ x = 5 - 8 \quad \text{or} \quad x = -5 - 8 \][/tex]

[tex]\[ x = -3 \quad \text{or} \quad x = -13 \][/tex]

Step 4 is correct according to the corrected version of Step 2.

Hence, Montiah made an error in Step 2.