21b^2-48b-45=

Solution for 21b^2-48b-45= equation:

Simplifying
21b2 + -48b + -45 = 0

Reorder the terms:
-45 + -48b + 21b2 = 0

Solving
-45 + -48b + 21b2 = 0

Solving for variable 'b'.

Factor out the Greatest Common Factor (GCF), '3'.
3(-15 + -16b + 7b2) = 0

Factor a trinomial.
3((-5 + -7b)(3 + -1b)) = 0

Ignore the factor 3.
Subproblem 1
Set the factor '(-5 + -7b)' equal to zero and attempt to solve:

Simplifying
-5 + -7b = 0

Solving
-5 + -7b = 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 + -7b = 0 + 5

Combine like terms: -5 + 5 = 0
0 + -7b = 0 + 5
-7b = 0 + 5

Combine like terms: 0 + 5 = 5
-7b = 5

Divide each side by '-7'.
b = -0.7142857143

Simplifying
b = -0.7142857143
Subproblem 2
Set the factor '(3 + -1b)' equal to zero and attempt to solve:

Simplifying
3 + -1b = 0

Solving
3 + -1b = 0

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

Add '-3' to each side of the equation.
3 + -3 + -1b = 0 + -3

Combine like terms: 3 + -3 = 0
0 + -1b = 0 + -3
-1b = 0 + -3

Combine like terms: 0 + -3 = -3
-1b = -3

Divide each side by '-1'.
b = 3

Simplifying
b = 3
Solution
b = {-0.7142857143, 3}