k^2+21k+20=0

Solution for k^2+21k+20=0 equation:

Simplifying
k2 + 21k + 20 = 0

Reorder the terms:
20 + 21k + k2 = 0

Solving
20 + 21k + k2 = 0

Solving for variable 'k'.

Factor a trinomial.
(20 + k)(1 + k) = 0

Subproblem 1
Set the factor '(20 + k)' equal to zero and attempt to solve:

Simplifying
20 + k = 0

Solving
20 + k = 0

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

Add '-20' to each side of the equation.
20 + -20 + k = 0 + -20

Combine like terms: 20 + -20 = 0
0 + k = 0 + -20
k = 0 + -20

Combine like terms: 0 + -20 = -20
k = -20

Simplifying
k = -20
Subproblem 2
Set the factor '(1 + k)' equal to zero and attempt to solve:

Simplifying
1 + k = 0

Solving
1 + k = 0

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

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

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

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

Simplifying
k = -1
Solution
k = {-20, -1}