Solve for x:
4 x^2 = 2.25
Rewrite the right-hand side of the equation.
2.25 = 9/4:
4 x^2 = 9/4
Divide both sides by a constant to simplify the equation.
Divide both sides by 4:
x^2 = 9/16
Eliminate the exponent on the left-hand side.
Take the square root of both sides:
x = 3/4 or x = -3/4