20z^2+21z+4=0

Solution for 20z^2+21z+4=0 equation:

Simplifying
20z2 + 21z + 4 = 0

Reorder the terms:
4 + 21z + 20z2 = 0

Solving
4 + 21z + 20z2 = 0

Solving for variable 'z'.

Factor a trinomial.
(4 + 5z)(1 + 4z) = 0

Subproblem 1
Set the factor '(4 + 5z)' equal to zero and attempt to solve:

Simplifying
4 + 5z = 0

Solving
4 + 5z = 0

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

Add '-4' to each side of the equation.
4 + -4 + 5z = 0 + -4

Combine like terms: 4 + -4 = 0
0 + 5z = 0 + -4
5z = 0 + -4

Combine like terms: 0 + -4 = -4
5z = -4

Divide each side by '5'.
z = -0.8

Simplifying
z = -0.8
Subproblem 2
Set the factor '(1 + 4z)' equal to zero and attempt to solve:

Simplifying
1 + 4z = 0

Solving
1 + 4z = 0

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

Add '-1' to each side of the equation.
1 + -1 + 4z = 0 + -1

Combine like terms: 1 + -1 = 0
0 + 4z = 0 + -1
4z = 0 + -1

Combine like terms: 0 + -1 = -1
4z = -1

Divide each side by '4'.
z = -0.25

Simplifying
z = -0.25
Solution
z = {-0.8, -0.25}