4a^2-90=31

Solution for 4a^2-90=31 equation:

Simplifying
4a2 + -90 = 31

Reorder the terms:
-90 + 4a2 = 31

Solving
-90 + 4a2 = 31

Solving for variable 'a'.

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

Add '90' to each side of the equation.
-90 + 90 + 4a2 = 31 + 90

Combine like terms: -90 + 90 = 0
0 + 4a2 = 31 + 90
4a2 = 31 + 90

Combine like terms: 31 + 90 = 121
4a2 = 121

Divide each side by '4'.
a2 = 30.25

Simplifying
a2 = 30.25

Take the square root of each side:
a = {-5.5, 5.5}