-2z^2+15=-21

Solution for -2z^2+15=-21 equation:

Simplifying
-2z2 + 15 = -21

Reorder the terms:
15 + -2z2 = -21

Solving
15 + -2z2 = -21

Solving for variable 'z'.

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

Add '-15' to each side of the equation.
15 + -15 + -2z2 = -21 + -15

Combine like terms: 15 + -15 = 0
0 + -2z2 = -21 + -15
-2z2 = -21 + -15

Combine like terms: -21 + -15 = -36
-2z2 = -36

Divide each side by '-2'.
z2 = 18

Simplifying
z2 = 18

Take the square root of each side:
z = {-4.242640687, 4.242640687}