-5x^2+4x=91

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Solution for -5x^2+4x=91 equation:


Simplifying
-5x2 + 4x = 91

Reorder the terms:
4x + -5x2 = 91

Solving
4x + -5x2 = 91

Solving for variable 'x'.

Reorder the terms:
-91 + 4x + -5x2 = 91 + -91

Combine like terms: 91 + -91 = 0
-91 + 4x + -5x2 = 0

Begin completing the square.  Divide all terms by
-5 the coefficient of the squared term: 

Divide each side by '-5'.
18.2 + -0.8x + x2 = 0

Move the constant term to the right:

Add '-18.2' to each side of the equation.
18.2 + -0.8x + -18.2 + x2 = 0 + -18.2

Reorder the terms:
18.2 + -18.2 + -0.8x + x2 = 0 + -18.2

Combine like terms: 18.2 + -18.2 = 0.0
0.0 + -0.8x + x2 = 0 + -18.2
-0.8x + x2 = 0 + -18.2

Combine like terms: 0 + -18.2 = -18.2
-0.8x + x2 = -18.2

The x term is -0.8x.  Take half its coefficient (-0.4).
Square it (0.16) and add it to both sides.

Add '0.16' to each side of the equation.
-0.8x + 0.16 + x2 = -18.2 + 0.16

Reorder the terms:
0.16 + -0.8x + x2 = -18.2 + 0.16

Combine like terms: -18.2 + 0.16 = -18.04
0.16 + -0.8x + x2 = -18.04

Factor a perfect square on the left side:
(x + -0.4)(x + -0.4) = -18.04

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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