3b^2+16b+21=0

Solution for 3b^2+16b+21=0 equation:

Simplifying
3b2 + 16b + 21 = 0

Reorder the terms:
21 + 16b + 3b2 = 0

Solving
21 + 16b + 3b2 = 0

Solving for variable 'b'.

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

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

Simplifying
3 + b = 0

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

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

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

Simplifying
b = -3
Subproblem 2
Set the factor '(7 + 3b)' equal to zero and attempt to solve:

Simplifying
7 + 3b = 0

Solving
7 + 3b = 0

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

Add '-7' to each side of the equation.
7 + -7 + 3b = 0 + -7

Combine like terms: 7 + -7 = 0
0 + 3b = 0 + -7
3b = 0 + -7

Combine like terms: 0 + -7 = -7
3b = -7

Divide each side by '3'.
b = -2.333333333

Simplifying
b = -2.333333333
Solution
b = {-3, -2.333333333}