x^2+3+x+15=90

Solution for x^2+3+x+15=90 equation:

Simplifying
x2 + 3 + x + 15 = 90

Reorder the terms:
3 + 15 + x + x2 = 90

Combine like terms: 3 + 15 = 18
18 + x + x2 = 90

Solving
18 + x + x2 = 90

Solving for variable 'x'.

Reorder the terms:
18 + -90 + x + x2 = 90 + -90

Combine like terms: 18 + -90 = -72
-72 + x + x2 = 90 + -90

Combine like terms: 90 + -90 = 0
-72 + x + x2 = 0

Factor a trinomial.
(-9 + -1x)(8 + -1x) = 0

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

Simplifying
-9 + -1x = 0

Solving
-9 + -1x = 0

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

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

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

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

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

Simplifying
x = -9
Subproblem 2
Set the factor '(8 + -1x)' equal to zero and attempt to solve:

Simplifying
8 + -1x = 0

Solving
8 + -1x = 0

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

Add '-8' to each side of the equation.
8 + -8 + -1x = 0 + -8

Combine like terms: 8 + -8 = 0
0 + -1x = 0 + -8
-1x = 0 + -8

Combine like terms: 0 + -8 = -8
-1x = -8

Divide each side by '-1'.
x = 8

Simplifying
x = 8
Solution
x = {-9, 8}