90=x^2+3+x+15

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

Simplifying
90 = x2 + 3 + x + 15

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

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

Solving
90 = 18 + x + x2

Solving for variable 'x'.

Combine like terms: 90 + -18 = 72
72 + -1x + -1x2 = 18 + x + x2 + -18 + -1x + -1x2

Reorder the terms:
72 + -1x + -1x2 = 18 + -18 + x + -1x + x2 + -1x2

Combine like terms: 18 + -18 = 0
72 + -1x + -1x2 = 0 + x + -1x + x2 + -1x2
72 + -1x + -1x2 = x + -1x + x2 + -1x2

Combine like terms: x + -1x = 0
72 + -1x + -1x2 = 0 + x2 + -1x2
72 + -1x + -1x2 = x2 + -1x2

Combine like terms: x2 + -1x2 = 0
72 + -1x + -1x2 = 0

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

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

Simplifying
9 + x = 0

Solving
9 + x = 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 + x = 0 + -9

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

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

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