u^2-7u-8=0

Solution for u^2-7u-8=0 equation:

Simplifying
u2 + -7u + -8 = 0

Reorder the terms:
-8 + -7u + u2 = 0

Solving
-8 + -7u + u2 = 0

Solving for variable 'u'.

Factor a trinomial.
(-1 + -1u)(8 + -1u) = 0

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

Simplifying
-1 + -1u = 0

Solving
-1 + -1u = 0

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

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

Combine like terms: -1 + 1 = 0
0 + -1u = 0 + 1
-1u = 0 + 1

Combine like terms: 0 + 1 = 1
-1u = 1

Divide each side by '-1'.
u = -1

Simplifying
u = -1
Subproblem 2
Set the factor '(8 + -1u)' equal to zero and attempt to solve:

Simplifying
8 + -1u = 0

Solving
8 + -1u = 0

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

Add '-8' to each side of the equation.
8 + -8 + -1u = 0 + -8

Combine like terms: 8 + -8 = 0
0 + -1u = 0 + -8
-1u = 0 + -8

Combine like terms: 0 + -8 = -8
-1u = -8

Divide each side by '-1'.
u = 8

Simplifying
u = 8
Solution
u = {-1, 8}