3r^2-15-7=5

Solution for 3r^2-15-7=5 equation:

Simplifying
3r2 + -15 + -7 = 5

Reorder the terms:
-15 + -7 + 3r2 = 5

Combine like terms: -15 + -7 = -22
-22 + 3r2 = 5

Solving
-22 + 3r2 = 5

Solving for variable 'r'.

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

Add '22' to each side of the equation.
-22 + 22 + 3r2 = 5 + 22

Combine like terms: -22 + 22 = 0
0 + 3r2 = 5 + 22
3r2 = 5 + 22

Combine like terms: 5 + 22 = 27
3r2 = 27

Divide each side by '3'.
r2 = 9

Simplifying
r2 = 9

Take the square root of each side:
r = {-3, 3}