3r^3+18r^2=21r

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Solution for 3r^3+18r^2=21r equation:


Simplifying
3r3 + 18r2 = 21r

Reorder the terms:
18r2 + 3r3 = 21r

Solving
18r2 + 3r3 = 21r

Solving for variable 'r'.

Reorder the terms:
-21r + 18r2 + 3r3 = 21r + -21r

Combine like terms: 21r + -21r = 0
-21r + 18r2 + 3r3 = 0

Factor out the Greatest Common Factor (GCF), '3r'.
3r(-7 + 6r + r2) = 0

Factor a trinomial.
3r((-7 + -1r)(1 + -1r)) = 0

Ignore the factor 3.

Subproblem 1

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

Subproblem 2

Set the factor '(-7 + -1r)' equal to zero and attempt to solve: Simplifying -7 + -1r = 0 Solving -7 + -1r = 0 Move all terms containing r to the left, all other terms to the right. Add '7' to each side of the equation. -7 + 7 + -1r = 0 + 7 Combine like terms: -7 + 7 = 0 0 + -1r = 0 + 7 -1r = 0 + 7 Combine like terms: 0 + 7 = 7 -1r = 7 Divide each side by '-1'. r = -7 Simplifying r = -7

Subproblem 3

Set the factor '(1 + -1r)' equal to zero and attempt to solve: Simplifying 1 + -1r = 0 Solving 1 + -1r = 0 Move all terms containing r to the left, all other terms to the right. Add '-1' to each side of the equation. 1 + -1 + -1r = 0 + -1 Combine like terms: 1 + -1 = 0 0 + -1r = 0 + -1 -1r = 0 + -1 Combine like terms: 0 + -1 = -1 -1r = -1 Divide each side by '-1'. r = 1 Simplifying r = 1

Solution

r = {0, -7, 1}

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