40-3b=b^2

Solution for 40-3b=b^2 equation:

Simplifying
40 + -3b = b2

Solving
40 + -3b = b2

Solving for variable 'b'.

Combine like terms: b2 + -1b2 = 0
40 + -3b + -1b2 = 0

Factor a trinomial.
(5 + -1b)(8 + b) = 0

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

Simplifying
5 + -1b = 0

Solving
5 + -1b = 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 + -1b = 0 + -5

Combine like terms: 5 + -5 = 0
0 + -1b = 0 + -5
-1b = 0 + -5

Combine like terms: 0 + -5 = -5
-1b = -5

Divide each side by '-1'.
b = 5

Simplifying
b = 5
Subproblem 2
Set the factor '(8 + b)' equal to zero and attempt to solve:

Simplifying
8 + b = 0

Solving
8 + b = 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 + b = 0 + -8

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

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

Simplifying
b = -8
Solution
b = {5, -8}