18=a(a-3)

Solution for 18=a(a-3) equation:

Simplifying
18 = a(a + -3)

Reorder the terms:
18 = a(-3 + a)
18 = (-3 * a + a * a)
18 = (-3a + a2)

Solving
18 = -3a + a2

Solving for variable 'a'.

Reorder the terms:
18 + 3a + -1a2 = -3a + 3a + a2 + -1a2

Combine like terms: -3a + 3a = 0
18 + 3a + -1a2 = 0 + a2 + -1a2
18 + 3a + -1a2 = a2 + -1a2

Combine like terms: a2 + -1a2 = 0
18 + 3a + -1a2 = 0

Factor a trinomial.
(6 + -1a)(3 + a) = 0

Subproblem 1
Set the factor '(6 + -1a)' equal to zero and attempt to solve:

Simplifying
6 + -1a = 0

Solving
6 + -1a = 0

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

Add '-6' to each side of the equation.
6 + -6 + -1a = 0 + -6

Combine like terms: 6 + -6 = 0
0 + -1a = 0 + -6
-1a = 0 + -6

Combine like terms: 0 + -6 = -6
-1a = -6

Divide each side by '-1'.
a = 6

Simplifying
a = 6
Subproblem 2
Set the factor '(3 + a)' equal to zero and attempt to solve:

Simplifying
3 + a = 0

Solving
3 + a = 0

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

Add '-3' to each side of the equation.
3 + -3 + a = 0 + -3

Combine like terms: 3 + -3 = 0
0 + a = 0 + -3
a = 0 + -3

Combine like terms: 0 + -3 = -3
a = -3

Simplifying
a = -3
Solution
a = {6, -3}