-x(x+2)=21

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Solution for -x(x+2)=21 equation:


Simplifying
-1x(x + 2) = 21

Reorder the terms:
-1x(2 + x) = 21
(2 * -1x + x * -1x) = 21
(-2x + -1x2) = 21

Solving
-2x + -1x2 = 21

Solving for variable 'x'.

Reorder the terms:
-21 + -2x + -1x2 = 21 + -21

Combine like terms: 21 + -21 = 0
-21 + -2x + -1x2 = 0

Factor out the Greatest Common Factor (GCF), '-1'.
-1(21 + 2x + x2) = 0

Ignore the factor -1.

Subproblem 1

Set the factor '(21 + 2x + x2)' equal to zero and attempt to solve: Simplifying 21 + 2x + x2 = 0 Solving 21 + 2x + x2 = 0 Begin completing the square. Move the constant term to the right: Add '-21' to each side of the equation. 21 + 2x + -21 + x2 = 0 + -21 Reorder the terms: 21 + -21 + 2x + x2 = 0 + -21 Combine like terms: 21 + -21 = 0 0 + 2x + x2 = 0 + -21 2x + x2 = 0 + -21 Combine like terms: 0 + -21 = -21 2x + x2 = -21 The x term is 2x. Take half its coefficient (1). Square it (1) and add it to both sides. Add '1' to each side of the equation. 2x + 1 + x2 = -21 + 1 Reorder the terms: 1 + 2x + x2 = -21 + 1 Combine like terms: -21 + 1 = -20 1 + 2x + x2 = -20 Factor a perfect square on the left side: (x + 1)(x + 1) = -20 Can't calculate square root of the right side. The solution to this equation could not be determined. This subproblem is being ignored because a solution could not be determined. The solution to this equation could not be determined.

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