d^2+21d+20=0

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

Simplifying
d2 + 21d + 20 = 0

Reorder the terms:
20 + 21d + d2 = 0

Solving
20 + 21d + d2 = 0

Solving for variable 'd'.

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

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

Simplifying
20 + d = 0

Solving
20 + d = 0

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

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

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

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

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

Simplifying
1 + d = 0

Solving
1 + d = 0

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

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

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

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

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