r^2+4r-285=0

Solution for r^2+4r-285=0 equation:

Simplifying
r2 + 4r + -285 = 0

Reorder the terms:
-285 + 4r + r2 = 0

Solving
-285 + 4r + r2 = 0

Solving for variable 'r'.

Factor a trinomial.
(-19 + -1r)(15 + -1r) = 0

Subproblem 1
Set the factor '(-19 + -1r)' equal to zero and attempt to solve:

Simplifying
-19 + -1r = 0

Solving
-19 + -1r = 0

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

Add '19' to each side of the equation.
-19 + 19 + -1r = 0 + 19

Combine like terms: -19 + 19 = 0
0 + -1r = 0 + 19
-1r = 0 + 19

Combine like terms: 0 + 19 = 19
-1r = 19

Divide each side by '-1'.
r = -19

Simplifying
r = -19
Subproblem 2
Set the factor '(15 + -1r)' equal to zero and attempt to solve:

Simplifying
15 + -1r = 0

Solving
15 + -1r = 0

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

Add '-15' to each side of the equation.
15 + -15 + -1r = 0 + -15

Combine like terms: 15 + -15 = 0
0 + -1r = 0 + -15
-1r = 0 + -15

Combine like terms: 0 + -15 = -15
-1r = -15

Divide each side by '-1'.
r = 15

Simplifying
r = 15
Solution
r = {-19, 15}