r^2-7r-20=-2

Solution for r^2-7r-20=-2 equation:

Simplifying
r2 + -7r + -20 = -2

Reorder the terms:
-20 + -7r + r2 = -2

Solving
-20 + -7r + r2 = -2

Solving for variable 'r'.

Reorder the terms:
-20 + 2 + -7r + r2 = -2 + 2

Combine like terms: -20 + 2 = -18
-18 + -7r + r2 = -2 + 2

Combine like terms: -2 + 2 = 0
-18 + -7r + r2 = 0

Factor a trinomial.
(-2 + -1r)(9 + -1r) = 0

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

Simplifying
-2 + -1r = 0

Solving
-2 + -1r = 0

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

Add '2' to each side of the equation.
-2 + 2 + -1r = 0 + 2

Combine like terms: -2 + 2 = 0
0 + -1r = 0 + 2
-1r = 0 + 2

Combine like terms: 0 + 2 = 2
-1r = 2

Divide each side by '-1'.
r = -2

Simplifying
r = -2
Subproblem 2
Set the factor '(9 + -1r)' equal to zero and attempt to solve:

Simplifying
9 + -1r = 0

Solving
9 + -1r = 0

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

Add '-9' to each side of the equation.
9 + -9 + -1r = 0 + -9

Combine like terms: 9 + -9 = 0
0 + -1r = 0 + -9
-1r = 0 + -9

Combine like terms: 0 + -9 = -9
-1r = -9

Divide each side by '-1'.
r = 9

Simplifying
r = 9
Solution
r = {-2, 9}