9f^2-3f-20=0

Solution for 9f^2-3f-20=0 equation:

Simplifying
9f2 + -3f + -20 = 0

Reorder the terms:
-20 + -3f + 9f2 = 0

Solving
-20 + -3f + 9f2 = 0

Solving for variable 'f'.

Factor a trinomial.
(-4 + -3f)(5 + -3f) = 0

Subproblem 1
Set the factor '(-4 + -3f)' equal to zero and attempt to solve:

Simplifying
-4 + -3f = 0

Solving
-4 + -3f = 0

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

Add '4' to each side of the equation.
-4 + 4 + -3f = 0 + 4

Combine like terms: -4 + 4 = 0
0 + -3f = 0 + 4
-3f = 0 + 4

Combine like terms: 0 + 4 = 4
-3f = 4

Divide each side by '-3'.
f = -1.333333333

Simplifying
f = -1.333333333
Subproblem 2
Set the factor '(5 + -3f)' equal to zero and attempt to solve:

Simplifying
5 + -3f = 0

Solving
5 + -3f = 0

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

Add '-5' to each side of the equation.
5 + -5 + -3f = 0 + -5

Combine like terms: 5 + -5 = 0
0 + -3f = 0 + -5
-3f = 0 + -5

Combine like terms: 0 + -5 = -5
-3f = -5

Divide each side by '-3'.
f = 1.666666667

Simplifying
f = 1.666666667
Solution
f = {-1.333333333, 1.666666667}