5a^2-a-18=0

Solution for 5a^2-a-18=0 equation:

Simplifying
5a2 + -1a + -18 = 0

Reorder the terms:
-18 + -1a + 5a2 = 0

Solving
-18 + -1a + 5a2 = 0

Solving for variable 'a'.

Factor a trinomial.
(-9 + -5a)(2 + -1a) = 0

Subproblem 1
Set the factor '(-9 + -5a)' equal to zero and attempt to solve:

Simplifying
-9 + -5a = 0

Solving
-9 + -5a = 0

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

Add '9' to each side of the equation.
-9 + 9 + -5a = 0 + 9

Combine like terms: -9 + 9 = 0
0 + -5a = 0 + 9
-5a = 0 + 9

Combine like terms: 0 + 9 = 9
-5a = 9

Divide each side by '-5'.
a = -1.8

Simplifying
a = -1.8
Subproblem 2
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
Solution
a = {-1.8, 2}