21b^2-39b-6=

Solution for 21b^2-39b-6= equation:

Simplifying
21b2 + -39b + -6 = 0

Reorder the terms:
-6 + -39b + 21b2 = 0

Solving
-6 + -39b + 21b2 = 0

Solving for variable 'b'.

Factor out the Greatest Common Factor (GCF), '3'.
3(-2 + -13b + 7b2) = 0

Factor a trinomial.
3((-1 + -7b)(2 + -1b)) = 0

Ignore the factor 3.
Subproblem 1
Set the factor '(-1 + -7b)' equal to zero and attempt to solve:

Simplifying
-1 + -7b = 0

Solving
-1 + -7b = 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 + -7b = 0 + 1

Combine like terms: -1 + 1 = 0
0 + -7b = 0 + 1
-7b = 0 + 1

Combine like terms: 0 + 1 = 1
-7b = 1

Divide each side by '-7'.
b = -0.1428571429

Simplifying
b = -0.1428571429
Subproblem 2
Set the factor '(2 + -1b)' equal to zero and attempt to solve:

Simplifying
2 + -1b = 0

Solving
2 + -1b = 0

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

Add '-2' to each side of the equation.
2 + -2 + -1b = 0 + -2

Combine like terms: 2 + -2 = 0
0 + -1b = 0 + -2
-1b = 0 + -2

Combine like terms: 0 + -2 = -2
-1b = -2

Divide each side by '-1'.
b = 2

Simplifying
b = 2
Solution
b = {-0.1428571429, 2}