40k^2-72k-16=0

Solution for 40k^2-72k-16=0 equation:

Simplifying
40k2 + -72k + -16 = 0

Reorder the terms:
-16 + -72k + 40k2 = 0

Solving
-16 + -72k + 40k2 = 0

Solving for variable 'k'.

Factor out the Greatest Common Factor (GCF), '8'.
8(-2 + -9k + 5k2) = 0

Factor a trinomial.
8((-1 + -5k)(2 + -1k)) = 0

Ignore the factor 8.
Subproblem 1
Set the factor '(-1 + -5k)' equal to zero and attempt to solve:

Simplifying
-1 + -5k = 0

Solving
-1 + -5k = 0

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

Add '1' to each side of the equation.
-1 + 1 + -5k = 0 + 1

Combine like terms: -1 + 1 = 0
0 + -5k = 0 + 1
-5k = 0 + 1

Combine like terms: 0 + 1 = 1
-5k = 1

Divide each side by '-5'.
k = -0.2

Simplifying
k = -0.2
Subproblem 2
Set the factor '(2 + -1k)' equal to zero and attempt to solve:

Simplifying
2 + -1k = 0

Solving
2 + -1k = 0

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

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

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

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

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

Simplifying
k = 2
Solution
k = {-0.2, 2}