8u^2-2u-15=0

Solution for 8u^2-2u-15=0 equation:

Simplifying
8u2 + -2u + -15 = 0

Reorder the terms:
-15 + -2u + 8u2 = 0

Solving
-15 + -2u + 8u2 = 0

Solving for variable 'u'.

Factor a trinomial.
(-5 + -4u)(3 + -2u) = 0

Subproblem 1
Set the factor '(-5 + -4u)' equal to zero and attempt to solve:

Simplifying
-5 + -4u = 0

Solving
-5 + -4u = 0

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

Add '5' to each side of the equation.
-5 + 5 + -4u = 0 + 5

Combine like terms: -5 + 5 = 0
0 + -4u = 0 + 5
-4u = 0 + 5

Combine like terms: 0 + 5 = 5
-4u = 5

Divide each side by '-4'.
u = -1.25

Simplifying
u = -1.25
Subproblem 2
Set the factor '(3 + -2u)' equal to zero and attempt to solve:

Simplifying
3 + -2u = 0

Solving
3 + -2u = 0

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

Add '-3' to each side of the equation.
3 + -3 + -2u = 0 + -3

Combine like terms: 3 + -3 = 0
0 + -2u = 0 + -3
-2u = 0 + -3

Combine like terms: 0 + -3 = -3
-2u = -3

Divide each side by '-2'.
u = 1.5

Simplifying
u = 1.5
Solution
u = {-1.25, 1.5}