(x*x)+8x=-15

Solution for (x*x)+8x=-15 equation:

Simplifying
(x * x) + 8x = -15

Multiply x * x
(x2) + 8x = -15
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.
(5 + x)(3 + x) = 0

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

Simplifying
5 + x = 0

Solving
5 + x = 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 + x = 0 + -5

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

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

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

Simplifying
3 + x = 0

Solving
3 + x = 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 + x = 0 + -3

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

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

Simplifying
x = -3
Solution
x = {-5, -3}