3x^2-0.75=90

Solution for 3x^2-0.75=90 equation:

Simplifying
3x2 + -0.75 = 90

Reorder the terms:
-0.75 + 3x2 = 90

Solving
-0.75 + 3x2 = 90

Solving for variable 'x'.

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

Add '0.75' to each side of the equation.
-0.75 + 0.75 + 3x2 = 90 + 0.75

Combine like terms: -0.75 + 0.75 = 0.00
0.00 + 3x2 = 90 + 0.75
3x2 = 90 + 0.75

Combine like terms: 90 + 0.75 = 90.75
3x2 = 90.75

Divide each side by '3'.
x2 = 30.25

Simplifying
x2 = 30.25

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