Using the quadratic formula to solve [tex]\(x^2 = 5 - x\)[/tex], what are the values of [tex]\(x\)[/tex]?

A. [tex]\(\frac{-1 \pm \sqrt{21}}{2}\)[/tex]

B. [tex]\(\frac{-1 \pm \sqrt{19i}}{2}\)[/tex]

C. [tex]\(\frac{5 \pm \sqrt{21}}{2}\)[/tex]

D. [tex]\(\frac{1 \pm \sqrt{19}i}{2}\)[/tex]



Answer :

To solve the equation [tex]\( x^2 = 5 - x \)[/tex] using the quadratic formula, let's follow the steps below in a detailed manner:

1. Rewrite the equation in standard form:
[tex]\[ x^2 + x - 5 = 0 \][/tex]

In this form, we can identify the coefficients [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(c\)[/tex] for the quadratic equation [tex]\(ax^2 + bx + c = 0\)[/tex]:
[tex]\[ a = 1, \quad b = 1, \quad c = -5 \][/tex]

2. Apply the quadratic formula:
The quadratic formula is given by:
[tex]\[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \][/tex]

3. Substitute the values of [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(c\)[/tex] into the formula:
[tex]\[ x = \frac{-(1) \pm \sqrt{(1)^2 - 4(1)(-5)}}{2(1)} \][/tex]

4. Simplify inside the square root:
[tex]\[ b^2 - 4ac = 1^2 - 4(1)(-5) = 1 + 20 = 21 \][/tex]

5. Plug this back into the formula:
[tex]\[ x = \frac{-1 \pm \sqrt{21}}{2} \][/tex]

Thus, the solutions to the equation are:
[tex]\[ x = \frac{-1 + \sqrt{21}}{2} \quad \text{and} \quad x = \frac{-1 - \sqrt{21}}{2} \][/tex]

Conclusion:

The values of [tex]\( x \)[/tex] that satisfy the equation [tex]\(x^2 = 5 - x\)[/tex] are:
[tex]\[ \boxed{\frac{-1 \pm \sqrt{21}}{2}} \][/tex]