2x^2-21=5

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

Simplifying
2x2 + -21 = 5

Reorder the terms:
-21 + 2x2 = 5

Solving
-21 + 2x2 = 5

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 + 2x2 = 5 + 21

Combine like terms: -21 + 21 = 0
0 + 2x2 = 5 + 21
2x2 = 5 + 21

Combine like terms: 5 + 21 = 26
2x2 = 26

Divide each side by '2'.
x2 = 13

Simplifying
x2 = 13

Take the square root of each side:
x = {-3.605551275, 3.605551275}