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4(x-2)(x+6)=4(x+2)

 Oct 12, 2016
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Solve for x:
4 (x-2) (x+6) = 4 (x+2)

Expand out terms of the left hand side:
4 x^2+16 x-48 = 4 (x+2)

Expand out terms of the right hand side:
4 x^2+16 x-48 = 4 x+8

Subtract 4 x+8 from both sides:
4 x^2+12 x-56 = 0

Divide both sides by 4:
x^2+3 x-14 = 0

Add 14 to both sides:
x^2+3 x = 14

Add 9/4 to both sides:
x^2+3 x+9/4 = 65/4

Write the left hand side as a square:
(x+3/2)^2 = 65/4

Take the square root of both sides:
x+3/2 = sqrt(65)/2 or x+3/2 = -sqrt(65)/2

Subtract 3/2 from both sides:
x = sqrt(65)/2-3/2 or x+3/2 = -sqrt(65)/2

Subtract 3/2 from both sides:
Answer: |x = sqrt(65)/2-3/2       or       x = -3/2-sqrt(65)/2

 Oct 12, 2016

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