45=s(s-4)

Solution for 45=s(s-4) equation:

Simplifying
45 = s(s + -4)

Reorder the terms:
45 = s(-4 + s)
45 = (-4 * s + s * s)
45 = (-4s + s2)

Solving
45 = -4s + s2

Solving for variable 's'.

Reorder the terms:
45 + 4s + -1s2 = -4s + 4s + s2 + -1s2

Combine like terms: -4s + 4s = 0
45 + 4s + -1s2 = 0 + s2 + -1s2
45 + 4s + -1s2 = s2 + -1s2

Combine like terms: s2 + -1s2 = 0
45 + 4s + -1s2 = 0

Factor a trinomial.
(9 + -1s)(5 + s) = 0

Subproblem 1
Set the factor '(9 + -1s)' equal to zero and attempt to solve:

Simplifying
9 + -1s = 0

Solving
9 + -1s = 0

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

Add '-9' to each side of the equation.
9 + -9 + -1s = 0 + -9

Combine like terms: 9 + -9 = 0
0 + -1s = 0 + -9
-1s = 0 + -9

Combine like terms: 0 + -9 = -9
-1s = -9

Divide each side by '-1'.
s = 9

Simplifying
s = 9
Subproblem 2
Set the factor '(5 + s)' equal to zero and attempt to solve:

Simplifying
5 + s = 0

Solving
5 + s = 0

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

Add '-5' to each side of the equation.
5 + -5 + s = 0 + -5

Combine like terms: 5 + -5 = 0
0 + s = 0 + -5
s = 0 + -5

Combine like terms: 0 + -5 = -5
s = -5

Simplifying
s = -5
Solution
s = {9, -5}