Use the quadratic formula to solve [tex]$x^2 + 9x + 10 = 0$[/tex]. What are the solutions to the equation? Round irrational solutions to the nearest tenth.

A. [tex]x = -8.9[/tex] and [tex]x = -0.14[/tex]
B. [tex]x = -7[/tex] and [tex]x = -1[/tex]
C. [tex]x = -7.7[/tex] and [tex]x = -1.3[/tex]
D. [tex]x = -10[/tex] and [tex]x = 2[/tex]



Answer :

To solve the quadratic equation [tex]\(x^2 + 9x + 10 = 0\)[/tex] using the quadratic formula, we'll follow these steps:

1. Identify the coefficients [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(c\)[/tex] from the quadratic equation [tex]\(ax^2 + bx + c = 0\)[/tex]. Here:
- [tex]\(a = 1\)[/tex]
- [tex]\(b = 9\)[/tex]
- [tex]\(c = 10\)[/tex]

2. Write down the quadratic formula:
[tex]\[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \][/tex]

3. Calculate the discriminant:
[tex]\[ b^2 - 4ac = 9^2 - 4 \cdot 1 \cdot 10 = 81 - 40 = 41 \][/tex]

4. Since the discriminant is positive, there are two real solutions. Substitute the discriminant and the coefficients into the quadratic formula to find the solutions:
[tex]\[ x = \frac{-9 \pm \sqrt{41}}{2 \cdot 1} \][/tex]

5. Calculate the two solutions separately:

First solution using the positive square root term:
[tex]\[ x_1 = \frac{-9 + \sqrt{41}}{2} \approx -1.2984378812835757 \][/tex]

Second solution using the negative square root term:
[tex]\[ x_2 = \frac{-9 - \sqrt{41}}{2} \approx -7.701562118716424 \][/tex]

6. Round the solutions to the nearest tenth:
[tex]\[ x_1 \approx -1.3 \][/tex]
[tex]\[ x_2 \approx -7.7 \][/tex]

So, the solutions to the equation [tex]\(x^2 + 9x + 10 = 0\)[/tex] are approximately [tex]\( x = -1.3 \)[/tex] and [tex]\( x = -7.7 \)[/tex].

Therefore, the correct answer is:
[tex]\[ x = -7.7 \text{ and } x = -1.3 \][/tex]