Problem

Solve the quadratic equation \(2x^2 - 6x - 8 = 0\) by completing the square.

Answer

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Answer

Finally, take the square root of both sides and solve for \(x\), which gives \(x = 1.5 + \sqrt{6.25}\) and \(x = 1.5 - \sqrt{6.25}\)

Steps

Step 1 :Firstly, divide the equation by the coefficient of \(x^2\), which is 2, to make it \(x^2 - 3x - 4 = 0\)

Step 2 :Next, rewrite the equation as \(x^2 - 3x = 4\)

Step 3 :Now, take half of the coefficient of \(x\), square it and add it to both sides of the equation. Half of -3 is -1.5 and \(-1.5^2 = 2.25\), so we add 2.25 to both sides to get \((x - 1.5)^2 = 6.25\)

Step 4 :Finally, take the square root of both sides and solve for \(x\), which gives \(x = 1.5 + \sqrt{6.25}\) and \(x = 1.5 - \sqrt{6.25}\)

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