2(x+5)(x-5)+21=7

Solution for 2(x+5)(x-5)+21=7 equation:

Simplifying
2(x + 5)(x + -5) + 21 = 7

Reorder the terms:
2(5 + x)(x + -5) + 21 = 7

Reorder the terms:
2(5 + x)(-5 + x) + 21 = 7

Multiply (5 + x) * (-5 + x)
2(5(-5 + x) + x(-5 + x)) + 21 = 7
2((-5 * 5 + x * 5) + x(-5 + x)) + 21 = 7
2((-25 + 5x) + x(-5 + x)) + 21 = 7
2(-25 + 5x + (-5 * x + x * x)) + 21 = 7
2(-25 + 5x + (-5x + x2)) + 21 = 7

Combine like terms: 5x + -5x = 0
2(-25 + 0 + x2) + 21 = 7
2(-25 + x2) + 21 = 7
(-25 * 2 + x2 * 2) + 21 = 7
(-50 + 2x2) + 21 = 7

Reorder the terms:
-50 + 21 + 2x2 = 7

Combine like terms: -50 + 21 = -29
-29 + 2x2 = 7

Solving
-29 + 2x2 = 7

Solving for variable 'x'.

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

Add '29' to each side of the equation.
-29 + 29 + 2x2 = 7 + 29

Combine like terms: -29 + 29 = 0
0 + 2x2 = 7 + 29
2x2 = 7 + 29

Combine like terms: 7 + 29 = 36
2x2 = 36

Divide each side by '2'.
x2 = 18

Simplifying
x2 = 18

Take the square root of each side:
x = {-4.242640687, 4.242640687}