(x+7)(x-3)-4x=0

Solution for (x+7)(x-3)-4x=0 equation:

Simplifying
(x + 7)(x + -3) + -4x = 0

Reorder the terms:
(7 + x)(x + -3) + -4x = 0

Reorder the terms:
(7 + x)(-3 + x) + -4x = 0

Multiply (7 + x) * (-3 + x)
(7(-3 + x) + x(-3 + x)) + -4x = 0
((-3 * 7 + x * 7) + x(-3 + x)) + -4x = 0
((-21 + 7x) + x(-3 + x)) + -4x = 0
(-21 + 7x + (-3 * x + x * x)) + -4x = 0
(-21 + 7x + (-3x + x2)) + -4x = 0

Combine like terms: 7x + -3x = 4x
(-21 + 4x + x2) + -4x = 0

Reorder the terms:
-21 + 4x + -4x + x2 = 0

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

Solving
-21 + x2 = 0

Solving for variable 'x'.

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

Add '21' to each side of the equation.
-21 + 21 + x2 = 0 + 21

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

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

Simplifying
x2 = 21

Take the square root of each side:
x = {-4.582575695, 4.582575695}