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Is the solution shown below correct? Explain.

[tex]\[
\begin{array}{l}
9x + 2 = 8x^2 + 6x \\
-8x^2 + 3x + 2 = 0 \\
x = \frac{-3 \pm \sqrt{3^2 - 4(-8)(2)}}{-16} \\
x = \frac{-3 \pm \sqrt{9 - (64)}}{-16} \\
x = \frac{3 \pm \sqrt{55i}}{16}
\end{array}
\][/tex]

Explain whether the solution is correct.

Sagot :

Let's review the solution step-by-step to determine its correctness.

### Step-by-Step Review:

1. Initial Equation:
[tex]\[ 9x + 2 = 8x^2 + 6x \][/tex]

2. Rearrange into Standard Form:
Subtract [tex]\(9x + 2\)[/tex] from both sides:
[tex]\[ 0 = 8x^2 + 6x - 9x - 2 \][/tex]
Simplify:
[tex]\[ 0 = 8x^2 - 3x - 2 \][/tex]
Rearrange to match standard quadratic form [tex]\(Ax^2 + Bx + C = 0\)[/tex]:
[tex]\[ -8x^2 + 3x + 2 = 0 \][/tex]

3. Identify Coefficients:
For the equation [tex]\(-8x^2 + 3x + 2 = 0\)[/tex], the coefficients are:
[tex]\[ A = -8, \quad B = 3, \quad C = 2 \][/tex]

4. Calculate the Discriminant:
The discriminant [tex]\(D\)[/tex] is given by the formula [tex]\(D = B^2 - 4AC\)[/tex]:
[tex]\[ D = 3^2 - 4(-8)(2) \][/tex]
Calculate the terms:
[tex]\[ D = 9 - (-64) \][/tex]
Simplify:
[tex]\[ D = 9 + 64 = 73 \][/tex]

5. Review the Provided Solution:
Let's look at the discriminant step in the provided solution:
[tex]\[ x = \frac{-3 \pm \sqrt{9 - (64)}}{-16} \][/tex]
This incorrectly sets the discriminant to:
[tex]\[ 9 - 64 = -55 \][/tex]
Then it states:
[tex]\[ x = \frac{-3 \pm \sqrt{-55i}}{-16} \text{,} \][/tex]
which is incorrect because the discriminant calculation steps should be:
[tex]\[ x = \frac{-3 \pm \sqrt{9 + 64}}{-16} = \frac{-3 \pm \sqrt{73}}{-16} \][/tex]

### Final Roots Calculation:
With the corrected discriminant [tex]\(D = 73\)[/tex]:
[tex]\[ x = \frac{-3 \pm \sqrt{73}}{-16} \][/tex]

This gives us two roots:
[tex]\[ x_1 = \frac{-3 + \sqrt{73}}{-16} \approx -0.3465 \][/tex]
[tex]\[ x_2 = \frac{-3 - \sqrt{73}}{-16} \approx 0.7215 \][/tex]

### Summary:

The provided solution contains mistakes in both the discriminant calculation and the final solution steps. The correct discriminant is [tex]\(73\)[/tex], and the correct roots of the quadratic equation [tex]\(-8x^2 + 3x + 2 = 0\)[/tex] are approximately [tex]\(-0.3465\)[/tex] and [tex]\(0.7215\)[/tex].