5+(4-x)*x=21

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Solution for 5+(4-x)*x=21 equation:


Simplifying
5 + (4 + -1x) * x = 21

Reorder the terms for easier multiplication:
5 + x(4 + -1x) = 21
5 + (4 * x + -1x * x) = 21
5 + (4x + -1x2) = 21

Solving
5 + 4x + -1x2 = 21

Solving for variable 'x'.

Reorder the terms:
5 + -21 + 4x + -1x2 = 21 + -21

Combine like terms: 5 + -21 = -16
-16 + 4x + -1x2 = 21 + -21

Combine like terms: 21 + -21 = 0
-16 + 4x + -1x2 = 0

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
16 + -4x + x2 = 0

Move the constant term to the right:

Add '-16' to each side of the equation.
16 + -4x + -16 + x2 = 0 + -16

Reorder the terms:
16 + -16 + -4x + x2 = 0 + -16

Combine like terms: 16 + -16 = 0
0 + -4x + x2 = 0 + -16
-4x + x2 = 0 + -16

Combine like terms: 0 + -16 = -16
-4x + x2 = -16

The x term is -4x.  Take half its coefficient (-2).
Square it (4) and add it to both sides.

Add '4' to each side of the equation.
-4x + 4 + x2 = -16 + 4

Reorder the terms:
4 + -4x + x2 = -16 + 4

Combine like terms: -16 + 4 = -12
4 + -4x + x2 = -12

Factor a perfect square on the left side:
(x + -2)(x + -2) = -12

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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