20b^2+21b-5=0

Solution for 20b^2+21b-5=0 equation:

Simplifying
20b2 + 21b + -5 = 0

Reorder the terms:
-5 + 21b + 20b2 = 0

Solving
-5 + 21b + 20b2 = 0

Solving for variable 'b'.

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

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

Simplifying
-5 + -4b = 0

Solving
-5 + -4b = 0

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

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

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

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

Divide each side by '-4'.
b = -1.25

Simplifying
b = -1.25
Subproblem 2
Set the factor '(1 + -5b)' equal to zero and attempt to solve:

Simplifying
1 + -5b = 0

Solving
1 + -5b = 0

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

Add '-1' to each side of the equation.
1 + -1 + -5b = 0 + -1

Combine like terms: 1 + -1 = 0
0 + -5b = 0 + -1
-5b = 0 + -1

Combine like terms: 0 + -1 = -1
-5b = -1

Divide each side by '-5'.
b = 0.2

Simplifying
b = 0.2
Solution
b = {-1.25, 0.2}