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Solve for [tex]\(x\)[/tex]:

[tex]\[ 2x^2 - 8x = -7 \][/tex]

A. [tex]\(-2 \pm \sqrt{2}\)[/tex]

B. [tex]\(-2 \pm 2\sqrt{2}\)[/tex]

C. [tex]\(\frac{2 \pm \sqrt{2}}{2}\)[/tex]

D. [tex]\(2 \pm \frac{\sqrt{2}}{2}\)[/tex]


Sagot :

To solve the quadratic equation [tex]\(2x^2 - 8x = -7\)[/tex], let's follow these steps:

1. Rewrite the equation in standard form:
[tex]\[ 2x^2 - 8x + 7 = 0 \][/tex]

2. Identify the coefficients:
The equation is in the form [tex]\(ax^2 + bx + c = 0\)[/tex] where:
[tex]\[ a = 2, \quad b = -8, \quad c = 7 \][/tex]

3. Calculate the discriminant:
The discriminant [tex]\(\Delta\)[/tex] is given by the formula:
[tex]\[ \Delta = b^2 - 4ac \][/tex]
Substituting the values of [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(c\)[/tex]:
[tex]\[ \Delta = (-8)^2 - 4 \cdot 2 \cdot 7 = 64 - 56 = 8 \][/tex]

4. Find the square root of the discriminant:
[tex]\[ \sqrt{\Delta} = \sqrt{8} = 2\sqrt{2} \][/tex]

5. Use the quadratic formula to find the solutions:
The quadratic formula is:
[tex]\[ x = \frac{-b \pm \sqrt{\Delta}}{2a} \][/tex]
Substituting the values of [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(\sqrt{\Delta}\)[/tex]:
[tex]\[ x = \frac{8 \pm 2\sqrt{2}}{4} \][/tex]
Simplifying further:
[tex]\[ x = \frac{8}{4} \pm \frac{2\sqrt{2}}{4} = 2 \pm \frac{\sqrt{2}}{2} \][/tex]

Therefore, the solutions to the equation [tex]\(2x^2 - 8x + 7 = 0\)[/tex] are:
[tex]\[ x = 2 + \frac{\sqrt{2}}{2} \quad \text{and} \quad x = 2 - \frac{\sqrt{2}}{2} \][/tex]

This matches the option [tex]\(\boxed{2 \pm \frac{\sqrt{2}}{2}}\)[/tex].