X^2+5-21=0

Solution for X^2+5-21=0 equation:

Simplifying
X2 + 5 + -21 = 0

Reorder the terms:
5 + -21 + X2 = 0

Combine like terms: 5 + -21 = -16
-16 + X2 = 0

Solving
-16 + X2 = 0

Solving for variable 'X'.

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

Add '16' to each side of the equation.
-16 + 16 + X2 = 0 + 16

Combine like terms: -16 + 16 = 0
0 + X2 = 0 + 16
X2 = 0 + 16

Combine like terms: 0 + 16 = 16
X2 = 16

Simplifying
X2 = 16

Take the square root of each side:
X = {-4, 4}