21b^2-102b-144=0

Solution for 21b^2-102b-144=0 equation:

Simplifying
21b2 + -102b + -144 = 0

Reorder the terms:
-144 + -102b + 21b2 = 0

Solving
-144 + -102b + 21b2 = 0

Solving for variable 'b'.

Factor out the Greatest Common Factor (GCF), '3'.
3(-48 + -34b + 7b2) = 0

Factor a trinomial.
3((-8 + -7b)(6 + -1b)) = 0

Ignore the factor 3.
Subproblem 1
Set the factor '(-8 + -7b)' equal to zero and attempt to solve:

Simplifying
-8 + -7b = 0

Solving
-8 + -7b = 0

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

Add '8' to each side of the equation.
-8 + 8 + -7b = 0 + 8

Combine like terms: -8 + 8 = 0
0 + -7b = 0 + 8
-7b = 0 + 8

Combine like terms: 0 + 8 = 8
-7b = 8

Divide each side by '-7'.
b = -1.142857143

Simplifying
b = -1.142857143
Subproblem 2
Set the factor '(6 + -1b)' equal to zero and attempt to solve:

Simplifying
6 + -1b = 0

Solving
6 + -1b = 0

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

Add '-6' to each side of the equation.
6 + -6 + -1b = 0 + -6

Combine like terms: 6 + -6 = 0
0 + -1b = 0 + -6
-1b = 0 + -6

Combine like terms: 0 + -6 = -6
-1b = -6

Divide each side by '-1'.
b = 6

Simplifying
b = 6
Solution
b = {-1.142857143, 6}