2a^2-21=0

Solution for 2a^2-21=0 equation:

Simplifying
2a2 + -21 = 0

Reorder the terms:
-21 + 2a2 = 0

Solving
-21 + 2a2 = 0

Solving for variable 'a'.

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

Add '21' to each side of the equation.
-21 + 21 + 2a2 = 0 + 21

Combine like terms: -21 + 21 = 0
0 + 2a2 = 0 + 21
2a2 = 0 + 21

Combine like terms: 0 + 21 = 21
2a2 = 21

Divide each side by '2'.
a2 = 10.5

Simplifying
a2 = 10.5

Take the square root of each side:
a = {-3.240370349, 3.240370349}