(x-21)(x+6)=

Solution for (x-21)(x+6)= equation:

Simplifying
(x + -21)(x + 6) = 0

Reorder the terms:
(-21 + x)(x + 6) = 0

Reorder the terms:
(-21 + x)(6 + x) = 0

Multiply (-21 + x) * (6 + x)
(-21(6 + x) + x(6 + x)) = 0
((6 * -21 + x * -21) + x(6 + x)) = 0
((-126 + -21x) + x(6 + x)) = 0
(-126 + -21x + (6 * x + x * x)) = 0
(-126 + -21x + (6x + x2)) = 0

Combine like terms: -21x + 6x = -15x
(-126 + -15x + x2) = 0

Solving
-126 + -15x + x2 = 0

Solving for variable 'x'.

Factor a trinomial.
(-6 + -1x)(21 + -1x) = 0

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 '(21 + -1x)' equal to zero and attempt to solve:

Simplifying
21 + -1x = 0

Solving
21 + -1x = 0

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

Add '-21' to each side of the equation.
21 + -21 + -1x = 0 + -21

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

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

Divide each side by '-1'.
x = 21

Simplifying
x = 21
Solution
x = {-6, 21}