To solve the quadratic equation \( x^2 + 2x - 8 = 0 \) by completing the square, follow these steps:
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Move the constant term to the other side of the equation: \[ x^2 + 2x = 8 \]
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Take half of the coefficient of \(x\) (which is 2), square it, and add it to both sides. Half of 2 is 1, and squaring it gives 1: \[ x^2 + 2x + 1 = 8 + 1 \] This simplifies to: \[ (x + 1)^2 = 9 \]
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Take the square root of both sides: \[ x + 1 = \pm 3 \]
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Solve for \(x\):
- For \(x + 1 = 3\): \[ x = 3 - 1 = 2 \]
- For \(x + 1 = -3\): \[ x = -3 - 1 = -4 \]
So the solutions are: \[ x = 2 \quad \text{and} \quad x = -4 \]
Since your original response options did not include \(-4\), it seems there was a mistake in my matching. Here are the correct answers based on the computed solutions.
Thus, the correct responses based on what you've provided are:
- \(x = 2\) (correct)
- \(x = -4\) (not provided in your options)
So, the complete correct solutions for \(x\) in the equation \(x^2 + 2x - 8 = 0\) are \(2\) and \(-4\).