(a^2-18a-40)=0

Solution for (a^2-18a-40)=0 equation:

Simplifying
(a2 + -18a + -40) = 0

Reorder the terms:
(-40 + -18a + a2) = 0

Remove parenthesis around (-40 + -18a + a2)
-40 + -18a + a2 = 0

Solving
-40 + -18a + a2 = 0

Solving for variable 'a'.

Factor a trinomial.
(-2 + -1a)(20 + -1a) = 0

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

Simplifying
-2 + -1a = 0

Solving
-2 + -1a = 0

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

Add '2' to each side of the equation.
-2 + 2 + -1a = 0 + 2

Combine like terms: -2 + 2 = 0
0 + -1a = 0 + 2
-1a = 0 + 2

Combine like terms: 0 + 2 = 2
-1a = 2

Divide each side by '-1'.
a = -2

Simplifying
a = -2
Subproblem 2
Set the factor '(20 + -1a)' equal to zero and attempt to solve:

Simplifying
20 + -1a = 0

Solving
20 + -1a = 0

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

Add '-20' to each side of the equation.
20 + -20 + -1a = 0 + -20

Combine like terms: 20 + -20 = 0
0 + -1a = 0 + -20
-1a = 0 + -20

Combine like terms: 0 + -20 = -20
-1a = -20

Divide each side by '-1'.
a = 20

Simplifying
a = 20
Solution
a = {-2, 20}