(x+1)(x-9)=39

Solution for (x+1)(x-9)=39 equation:

Simplifying
(x + 1)(x + -9) = 39

Reorder the terms:
(1 + x)(x + -9) = 39

Reorder the terms:
(1 + x)(-9 + x) = 39

Multiply (1 + x) * (-9 + x)
(1(-9 + x) + x(-9 + x)) = 39
((-9 * 1 + x * 1) + x(-9 + x)) = 39
((-9 + 1x) + x(-9 + x)) = 39
(-9 + 1x + (-9 * x + x * x)) = 39
(-9 + 1x + (-9x + x2)) = 39

Combine like terms: 1x + -9x = -8x
(-9 + -8x + x2) = 39

Solving
-9 + -8x + x2 = 39

Solving for variable 'x'.

Reorder the terms:
-9 + -39 + -8x + x2 = 39 + -39

Combine like terms: -9 + -39 = -48
-48 + -8x + x2 = 39 + -39

Combine like terms: 39 + -39 = 0
-48 + -8x + x2 = 0

Factor a trinomial.
(-4 + -1x)(12 + -1x) = 0

Subproblem 1
Set the factor '(-4 + -1x)' equal to zero and attempt to solve:

Simplifying
-4 + -1x = 0

Solving
-4 + -1x = 0

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

Add '4' to each side of the equation.
-4 + 4 + -1x = 0 + 4

Combine like terms: -4 + 4 = 0
0 + -1x = 0 + 4
-1x = 0 + 4

Combine like terms: 0 + 4 = 4
-1x = 4

Divide each side by '-1'.
x = -4

Simplifying
x = -4
Subproblem 2
Set the factor '(12 + -1x)' equal to zero and attempt to solve:

Simplifying
12 + -1x = 0

Solving
12 + -1x = 0

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

Add '-12' to each side of the equation.
12 + -12 + -1x = 0 + -12

Combine like terms: 12 + -12 = 0
0 + -1x = 0 + -12
-1x = 0 + -12

Combine like terms: 0 + -12 = -12
-1x = -12

Divide each side by '-1'.
x = 12

Simplifying
x = 12
Solution
x = {-4, 12}