9y^2-4=0

Solution for 9y^2-4=0 equation:

Simplifying
9y2 + -4 = 0

Reorder the terms:
-4 + 9y2 = 0

Solving
-4 + 9y2 = 0

Solving for variable 'y'.

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

Add '4' to each side of the equation.
-4 + 4 + 9y2 = 0 + 4

Combine like terms: -4 + 4 = 0
0 + 9y2 = 0 + 4
9y2 = 0 + 4

Combine like terms: 0 + 4 = 4
9y2 = 4

Divide each side by '9'.
y2 = 0.4444444444

Simplifying
y2 = 0.4444444444

Take the square root of each side:
y = {-0.666666667, 0.666666667}