(r+1)(r-2)=

Solution for (r+1)(r-2)= equation:

Simplifying
(r + 1)(r + -2) = 0

Reorder the terms:
(1 + r)(r + -2) = 0

Reorder the terms:
(1 + r)(-2 + r) = 0

Multiply (1 + r) * (-2 + r)
(1(-2 + r) + r(-2 + r)) = 0
((-2 * 1 + r * 1) + r(-2 + r)) = 0
((-2 + 1r) + r(-2 + r)) = 0
(-2 + 1r + (-2 * r + r * r)) = 0
(-2 + 1r + (-2r + r2)) = 0

Combine like terms: 1r + -2r = -1r
(-2 + -1r + r2) = 0

Solving
-2 + -1r + r2 = 0

Solving for variable 'r'.

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

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

Simplifying
-1 + -1r = 0

Solving
-1 + -1r = 0

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

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

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

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

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

Simplifying
r = -1
Subproblem 2
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
Solution
r = {-1, 2}