7y^2-21=0

Solution for 7y^2-21=0 equation:

Simplifying
7y2 + -21 = 0

Reorder the terms:
-21 + 7y2 = 0

Solving
-21 + 7y2 = 0

Solving for variable 'y'.

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

Add '21' to each side of the equation.
-21 + 21 + 7y2 = 0 + 21

Combine like terms: -21 + 21 = 0
0 + 7y2 = 0 + 21
7y2 = 0 + 21

Combine like terms: 0 + 21 = 21
7y2 = 21

Divide each side by '7'.
y2 = 3

Simplifying
y2 = 3

Take the square root of each side:
y = {-1.732050808, 1.732050808}