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Solve 2x2 + 3x = −8.

User Belky
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1 Answer

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Solve for x:
x (2 x + 3) = -8

Expand out terms of the left hand side:
2 x^2 + 3 x = -8

Divide both sides by 2:
x^2 + (3 x)/2 = -4

Add 9/16 to both sides:
x^2 + (3 x)/2 + 9/16 = -55/16

Write the left hand side as a square:
(x + 3/4)^2 = -55/16

Take the square root of both sides:
x + 3/4 = (i sqrt(55))/4 or x + 3/4 = -(i sqrt(55))/4

Subtract 3/4 from both sides:
x = (i sqrt(55))/4 - 3/4 or x + 3/4 = -(i sqrt(55))/4

Subtract 3/4 from both sides:

Answer: x = (i sqrt(55))/4 - 3/4 or x = -(i sqrt(55))/4 - 3/4

No real solutions
User Vinay
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