A^2-12A-9=4

Solution for A^2-12A-9=4 equation:

Simplifying
A2 + -12A + -9 = 4

Reorder the terms:
-9 + -12A + A2 = 4

Solving
-9 + -12A + A2 = 4

Solving for variable 'A'.

Reorder the terms:
-9 + -4 + -12A + A2 = 4 + -4

Combine like terms: -9 + -4 = -13
-13 + -12A + A2 = 4 + -4

Combine like terms: 4 + -4 = 0
-13 + -12A + A2 = 0

Factor a trinomial.
(-1 + -1A)(13 + -1A) = 0

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

Simplifying
-1 + -1A = 0

Solving
-1 + -1A = 0

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

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

Combine like terms: -1 + 1 = 0
0 + -1A = 0 + 1
-1A = 0 + 1

Combine like terms: 0 + 1 = 1
-1A = 1

Divide each side by '-1'.
A = -1

Simplifying
A = -1
Subproblem 2
Set the factor '(13 + -1A)' equal to zero and attempt to solve:

Simplifying
13 + -1A = 0

Solving
13 + -1A = 0

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

Add '-13' to each side of the equation.
13 + -13 + -1A = 0 + -13

Combine like terms: 13 + -13 = 0
0 + -1A = 0 + -13
-1A = 0 + -13

Combine like terms: 0 + -13 = -13
-1A = -13

Divide each side by '-1'.
A = 13

Simplifying
A = 13
Solution
A = {-1, 13}