-r^2=16-8r

Solution for -r^2=16-8r equation:

Simplifying
-1r2 = 16 + -8r

Solving
-1r2 = 16 + -8r

Solving for variable 'r'.

Reorder the terms:
-16 + 8r + -1r2 = 16 + -8r + -16 + 8r

Reorder the terms:
-16 + 8r + -1r2 = 16 + -16 + -8r + 8r

Combine like terms: 16 + -16 = 0
-16 + 8r + -1r2 = 0 + -8r + 8r
-16 + 8r + -1r2 = -8r + 8r

Combine like terms: -8r + 8r = 0
-16 + 8r + -1r2 = 0

Factor a trinomial.
(-4 + r)(4 + -1r) = 0

Subproblem 1
Set the factor '(-4 + r)' equal to zero and attempt to solve:

Simplifying
-4 + r = 0

Solving
-4 + r = 0

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

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

Combine like terms: -4 + 4 = 0
0 + r = 0 + 4
r = 0 + 4

Combine like terms: 0 + 4 = 4
r = 4

Simplifying
r = 4
Subproblem 2
Set the factor '(4 + -1r)' equal to zero and attempt to solve:

Simplifying
4 + -1r = 0

Solving
4 + -1r = 0

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

Add '-4' to each side of the equation.
4 + -4 + -1r = 0 + -4

Combine like terms: 4 + -4 = 0
0 + -1r = 0 + -4
-1r = 0 + -4

Combine like terms: 0 + -4 = -4
-1r = -4

Divide each side by '-1'.
r = 4

Simplifying
r = 4
Solution
r = {4, 4}