(x+10)(x-6)=4x+21

Solution for (x+10)(x-6)=4x+21 equation:

Simplifying
(x + 10)(x + -6) = 4x + 21

Reorder the terms:
(10 + x)(x + -6) = 4x + 21

Reorder the terms:
(10 + x)(-6 + x) = 4x + 21

Multiply (10 + x) * (-6 + x)
(10(-6 + x) + x(-6 + x)) = 4x + 21
((-6 * 10 + x * 10) + x(-6 + x)) = 4x + 21
((-60 + 10x) + x(-6 + x)) = 4x + 21
(-60 + 10x + (-6 * x + x * x)) = 4x + 21
(-60 + 10x + (-6x + x2)) = 4x + 21

Combine like terms: 10x + -6x = 4x
(-60 + 4x + x2) = 4x + 21

Reorder the terms:
-60 + 4x + x2 = 21 + 4x

Add '-4x' to each side of the equation.
-60 + 4x + -4x + x2 = 21 + 4x + -4x

Combine like terms: 4x + -4x = 0
-60 + 0 + x2 = 21 + 4x + -4x
-60 + x2 = 21 + 4x + -4x

Combine like terms: 4x + -4x = 0
-60 + x2 = 21 + 0
-60 + x2 = 21

Solving
-60 + x2 = 21

Solving for variable 'x'.

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

Add '60' to each side of the equation.
-60 + 60 + x2 = 21 + 60

Combine like terms: -60 + 60 = 0
0 + x2 = 21 + 60
x2 = 21 + 60

Combine like terms: 21 + 60 = 81
x2 = 81

Simplifying
x2 = 81

Take the square root of each side:
x = {-9, 9}