(-7x^2+21x)=-126

Solution for (-7x^2+21x)=-126 equation:

Simplifying
(-7x2 + 21x) = -126

Reorder the terms:
(21x + -7x2) = -126

Remove parenthesis around (21x + -7x2)
21x + -7x2 = -126

Solving
21x + -7x2 = -126

Solving for variable 'x'.

Reorder the terms:
126 + 21x + -7x2 = -126 + 126

Combine like terms: -126 + 126 = 0
126 + 21x + -7x2 = 0

Factor out the Greatest Common Factor (GCF), '7'.
7(18 + 3x + -1x2) = 0

Factor a trinomial.
7((6 + -1x)(3 + x)) = 0

Ignore the factor 7.
Subproblem 1
Set the factor '(6 + -1x)' equal to zero and attempt to solve:

Simplifying
6 + -1x = 0

Solving
6 + -1x = 0

Move all terms containing x to the left, all other terms to the right.

Add '-6' to each side of the equation.
6 + -6 + -1x = 0 + -6

Combine like terms: 6 + -6 = 0
0 + -1x = 0 + -6
-1x = 0 + -6

Combine like terms: 0 + -6 = -6
-1x = -6

Divide each side by '-1'.
x = 6

Simplifying
x = 6
Subproblem 2
Set the factor '(3 + x)' equal to zero and attempt to solve:

Simplifying
3 + x = 0

Solving
3 + x = 0

Move all terms containing x to the left, all other terms to the right.

Add '-3' to each side of the equation.
3 + -3 + x = 0 + -3

Combine like terms: 3 + -3 = 0
0 + x = 0 + -3
x = 0 + -3

Combine like terms: 0 + -3 = -3
x = -3

Simplifying
x = -3
Solution
x = {6, -3}