r^2+64+16r=400

Solution for r^2+64+16r=400 equation:

Simplifying
r2 + 64 + 16r = 400

Reorder the terms:
64 + 16r + r2 = 400

Solving
64 + 16r + r2 = 400

Solving for variable 'r'.

Reorder the terms:
64 + -400 + 16r + r2 = 400 + -400

Combine like terms: 64 + -400 = -336
-336 + 16r + r2 = 400 + -400

Combine like terms: 400 + -400 = 0
-336 + 16r + r2 = 0

Factor a trinomial.
(-28 + -1r)(12 + -1r) = 0

Subproblem 1
Set the factor '(-28 + -1r)' equal to zero and attempt to solve:

Simplifying
-28 + -1r = 0

Solving
-28 + -1r = 0

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

Add '28' to each side of the equation.
-28 + 28 + -1r = 0 + 28

Combine like terms: -28 + 28 = 0
0 + -1r = 0 + 28
-1r = 0 + 28

Combine like terms: 0 + 28 = 28
-1r = 28

Divide each side by '-1'.
r = -28

Simplifying
r = -28
Subproblem 2
Set the factor '(12 + -1r)' equal to zero and attempt to solve:

Simplifying
12 + -1r = 0

Solving
12 + -1r = 0

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

Add '-12' to each side of the equation.
12 + -12 + -1r = 0 + -12

Combine like terms: 12 + -12 = 0
0 + -1r = 0 + -12
-1r = 0 + -12

Combine like terms: 0 + -12 = -12
-1r = -12

Divide each side by '-1'.
r = 12

Simplifying
r = 12
Solution
r = {-28, 12}