Question

Solve the quadratic equation.
x^2 + 9x - 15 = 0
answers below:
x = 9+- square root 21 / 2
x = 9 +- square root 141 / 2
x = -9 +- square root 141 / 2
x = -9 +- square root 21 / 2

Answer 1

To solve the quadratic equation \( x^2 + 9x - 15 = 0 \), we can use the quadratic formula, which is given by:

\[
x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}
\]

In this equation, the coefficients are:
- \( a = 1 \)
- \( b = 9 \)
- \( c = -15 \)

Let's calculate the discriminant (\( b^2 - 4ac \)):

\[
b^2 - 4ac = 9^2 - 4 \cdot 1 \cdot (-15) = 81 + 60 = 141
\]

Now, we can plug the values back into the quadratic formula:

\[
x = \frac{-9 \pm \sqrt{141}}{2 \cdot 1}
\]

This simplifies to:

\[
x = \frac{-9 \pm \sqrt{141}}{2}
\]

Based on the choices you provided, the correct answer is:

\[
x = -9 \pm \frac{\sqrt{141}}{2}
\]

So, the answer is:

\[
x = -9 \pm \frac{\sqrt{141}}{2}
\]

This corresponds to the option:

**x = -9 ± square root 141 / 2**.