f^2-3f-18=0

Solution for f^2-3f-18=0 equation:

Simplifying
f2 + -3f + -18 = 0

Reorder the terms:
-18 + -3f + f2 = 0

Solving
-18 + -3f + f2 = 0

Solving for variable 'f'.

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

Subproblem 1
Set the factor '(-3 + -1f)' equal to zero and attempt to solve:

Simplifying
-3 + -1f = 0

Solving
-3 + -1f = 0

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

Add '3' to each side of the equation.
-3 + 3 + -1f = 0 + 3

Combine like terms: -3 + 3 = 0
0 + -1f = 0 + 3
-1f = 0 + 3

Combine like terms: 0 + 3 = 3
-1f = 3

Divide each side by '-1'.
f = -3

Simplifying
f = -3
Subproblem 2
Set the factor '(6 + -1f)' equal to zero and attempt to solve:

Simplifying
6 + -1f = 0

Solving
6 + -1f = 0

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

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

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

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

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

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