-4=b^2-4b

Solution for -4=b^2-4b equation:

Simplifying
-4 = b2 + -4b

Reorder the terms:
-4 = -4b + b2

Solving
-4 = -4b + b2

Solving for variable 'b'.

Reorder the terms:
-4 + 4b + -1b2 = -4b + 4b + b2 + -1b2

Combine like terms: -4b + 4b = 0
-4 + 4b + -1b2 = 0 + b2 + -1b2
-4 + 4b + -1b2 = b2 + -1b2

Combine like terms: b2 + -1b2 = 0
-4 + 4b + -1b2 = 0

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

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

Simplifying
-2 + b = 0

Solving
-2 + b = 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 + b = 0 + 2

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

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

Simplifying
b = 2
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 = {2, 2}