Complete the square to solve the following quadratic equation: x2+2x−8=0.(1 point)

Responses

x=10, x=−8
x equals 10 ,  x equals negative 8

x=−2, x=4
x equals negative 2 ,  x equals 4

x=−10, x=8
x equals negative 10 ,  x equals 8

x=2, x=−4

1 answer

To complete the square for the equation \(x^2 + 2x - 8 = 0\), we will first move the constant to the other side:

\[ x^2 + 2x = 8 \]

Next, we take the coefficient of \(x\) (which is \(2\)), divide it by \(2\) to get \(1\), and then square it to get \(1^2 = 1\). We add this square to both sides of the equation:

\[ x^2 + 2x + 1 = 8 + 1 \]

This simplifies to:

\[ (x + 1)^2 = 9 \]

Next, we take the square root of both sides:

\[ x + 1 = \pm 3 \]

Now, we can solve for \(x\):

  1. \(x + 1 = 3 \implies x = 2\)
  2. \(x + 1 = -3 \implies x = -4\)

Thus, the solutions to the equation \(x^2 + 2x - 8 = 0\) are:

\[ x = 2 \quad \text{and} \quad x = -4 \]

Therefore, the correct response is:

x=2, x=−4
(x equals 2, x equals negative 4)