3b^2-7b-20=0

Solution for 3b^2-7b-20=0 equation:

Simplifying
3b2 + -7b + -20 = 0

Reorder the terms:
-20 + -7b + 3b2 = 0

Solving
-20 + -7b + 3b2 = 0

Solving for variable 'b'.

Factor a trinomial.
(-5 + -3b)(4 + -1b) = 0

Subproblem 1
Set the factor '(-5 + -3b)' equal to zero and attempt to solve:

Simplifying
-5 + -3b = 0

Solving
-5 + -3b = 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 + -3b = 0 + 5

Combine like terms: -5 + 5 = 0
0 + -3b = 0 + 5
-3b = 0 + 5

Combine like terms: 0 + 5 = 5
-3b = 5

Divide each side by '-3'.
b = -1.666666667

Simplifying
b = -1.666666667
Subproblem 2
Set the factor '(4 + -1b)' equal to zero and attempt to solve:

Simplifying
4 + -1b = 0

Solving
4 + -1b = 0

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

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

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

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

Divide each side by '-1'.
b = 4

Simplifying
b = 4
Solution
b = {-1.666666667, 4}