4x^2-5-21=0

Solution for 4x^2-5-21=0 equation:

Simplifying
4x2 + -5 + -21 = 0

Reorder the terms:
-5 + -21 + 4x2 = 0

Combine like terms: -5 + -21 = -26
-26 + 4x2 = 0

Solving
-26 + 4x2 = 0

Solving for variable 'x'.

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

Add '26' to each side of the equation.
-26 + 26 + 4x2 = 0 + 26

Combine like terms: -26 + 26 = 0
0 + 4x2 = 0 + 26
4x2 = 0 + 26

Combine like terms: 0 + 26 = 26
4x2 = 26

Divide each side by '4'.
x2 = 6.5

Simplifying
x2 = 6.5

Take the square root of each side:
x = {-2.549509757, 2.549509757}