8x^2+5x+21=0

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Solution for 8x^2+5x+21=0 equation:


Simplifying
8x2 + 5x + 21 = 0

Reorder the terms:
21 + 5x + 8x2 = 0

Solving
21 + 5x + 8x2 = 0

Solving for variable 'x'.

Begin completing the square.  Divide all terms by
8 the coefficient of the squared term: 

Divide each side by '8'.
2.625 + 0.625x + x2 = 0

Move the constant term to the right:

Add '-2.625' to each side of the equation.
2.625 + 0.625x + -2.625 + x2 = 0 + -2.625

Reorder the terms:
2.625 + -2.625 + 0.625x + x2 = 0 + -2.625

Combine like terms: 2.625 + -2.625 = 0.000
0.000 + 0.625x + x2 = 0 + -2.625
0.625x + x2 = 0 + -2.625

Combine like terms: 0 + -2.625 = -2.625
0.625x + x2 = -2.625

The x term is 0.625x.  Take half its coefficient (0.3125).
Square it (0.09765625) and add it to both sides.

Add '0.09765625' to each side of the equation.
0.625x + 0.09765625 + x2 = -2.625 + 0.09765625

Reorder the terms:
0.09765625 + 0.625x + x2 = -2.625 + 0.09765625

Combine like terms: -2.625 + 0.09765625 = -2.52734375
0.09765625 + 0.625x + x2 = -2.52734375

Factor a perfect square on the left side:
(x + 0.3125)(x + 0.3125) = -2.52734375

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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