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4x^2+8x+23

 Apr 5, 2016
 #1
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It has only "complex" solution:

 

Solve for x:
4 x^2+8 x+23 = 0

Divide both sides by 4:
x^2+2 x+23/4 = 0

Subtract 23/4 from both sides:
x^2+2 x = -23/4

Add 1 to both sides:
x^2+2 x+1 = -19/4

Write the left hand side as a square:
(x+1)^2 = -19/4

Take the square root of both sides:
x+1 = (i sqrt(19))/2 or x+1 = 1/2 (-i) sqrt(19)

Subtract 1 from both sides:
x = (i sqrt(19))/2-1 or x+1 = 1/2 (-i) sqrt(19)

Subtract 1 from both sides:
Answer: |  x = (i sqrt(19))/2-1           or         x = 1/2 (-i) sqrt(19)-1

 Apr 5, 2016

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