X*X-8X=-15

Solution for X*X-8X=-15 equation:

Simplifying
X * X + -8X = -15

Multiply X * X
X2 + -8X = -15

Reorder the terms:
-8X + X2 = -15

Solving
-8X + X2 = -15

Solving for variable 'X'.

Reorder the terms:
15 + -8X + X2 = -15 + 15

Combine like terms: -15 + 15 = 0
15 + -8X + X2 = 0

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

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

Simplifying
3 + -1X = 0

Solving
3 + -1X = 0

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

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

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

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

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

Simplifying
X = 3
Subproblem 2
Set the factor '(5 + -1X)' equal to zero and attempt to solve:

Simplifying
5 + -1X = 0

Solving
5 + -1X = 0

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

Add '-5' to each side of the equation.
5 + -5 + -1X = 0 + -5

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

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

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

Simplifying
X = 5
Solution
X = {3, 5}