5z^2-20+15=0

Solution for 5z^2-20+15=0 equation:

Simplifying
5z2 + -20 + 15 = 0

Reorder the terms:
-20 + 15 + 5z2 = 0

Combine like terms: -20 + 15 = -5
-5 + 5z2 = 0

Solving
-5 + 5z2 = 0

Solving for variable 'z'.

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

Add '5' to each side of the equation.
-5 + 5 + 5z2 = 0 + 5

Combine like terms: -5 + 5 = 0
0 + 5z2 = 0 + 5
5z2 = 0 + 5

Combine like terms: 0 + 5 = 5
5z2 = 5

Divide each side by '5'.
z2 = 1

Simplifying
z2 = 1

Take the square root of each side:
z = {-1, 1}