To solve the quadratic equation \(x^2 + 2x - 8 = 0\) by completing the square, we follow these steps:
-
Rearrange the equation:
\[ x^2 + 2x = 8 \] -
Complete the square on the left side. Take half of the coefficient of \(x\) (which is \(2\)), square it, and add it to both sides:
\[ \left(\frac{2}{2}\right)^2 = 1 \]
So we add \(1\) to both sides:
\[ x^2 + 2x + 1 = 8 + 1 \]
This simplifies to:
\[ (x + 1)^2 = 9 \] -
Take the square root of both sides:
\[ x + 1 = \pm 3 \] -
Solve for \(x\) by isolating \(x\):
- For the positive case:
\[ x + 1 = 3 \quad \Rightarrow \quad x = 3 - 1 = 2 \] - For the negative case:
\[ x + 1 = -3 \quad \Rightarrow \quad x = -3 - 1 = -4 \]
- For the positive case:
Thus, the solutions are \(x = 2\) and \(x = -4\).
The correct response is: x = 2, x = -4.