u^3-81u=0

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Solution for u^3-81u=0 equation:


Simplifying
u3 + -81u = 0

Reorder the terms:
-81u + u3 = 0

Solving
-81u + u3 = 0

Solving for variable 'u'.

Factor out the Greatest Common Factor (GCF), 'u'.
u(-81 + u2) = 0

Factor a difference between two squares.
u((9 + u)(-9 + u)) = 0

Subproblem 1

Set the factor 'u' equal to zero and attempt to solve: Simplifying u = 0 Solving u = 0 Move all terms containing u to the left, all other terms to the right. Simplifying u = 0

Subproblem 2

Set the factor '(9 + u)' equal to zero and attempt to solve: Simplifying 9 + u = 0 Solving 9 + u = 0 Move all terms containing u to the left, all other terms to the right. Add '-9' to each side of the equation. 9 + -9 + u = 0 + -9 Combine like terms: 9 + -9 = 0 0 + u = 0 + -9 u = 0 + -9 Combine like terms: 0 + -9 = -9 u = -9 Simplifying u = -9

Subproblem 3

Set the factor '(-9 + u)' equal to zero and attempt to solve: Simplifying -9 + u = 0 Solving -9 + u = 0 Move all terms containing u to the left, all other terms to the right. Add '9' to each side of the equation. -9 + 9 + u = 0 + 9 Combine like terms: -9 + 9 = 0 0 + u = 0 + 9 u = 0 + 9 Combine like terms: 0 + 9 = 9 u = 9 Simplifying u = 9

Solution

u = {0, -9, 9}

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