r^2-2r=15

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Solution for r^2-2r=15 equation:


Simplifying
r2 + -2r = 15

Reorder the terms:
-2r + r2 = 15

Solving
-2r + r2 = 15

Solving for variable 'r'.

Reorder the terms:
-15 + -2r + r2 = 15 + -15

Combine like terms: 15 + -15 = 0
-15 + -2r + r2 = 0

Factor a trinomial.
(-3 + -1r)(5 + -1r) = 0

Subproblem 1

Set the factor '(-3 + -1r)' equal to zero and attempt to solve: Simplifying -3 + -1r = 0 Solving -3 + -1r = 0 Move all terms containing r to the left, all other terms to the right. Add '3' to each side of the equation. -3 + 3 + -1r = 0 + 3 Combine like terms: -3 + 3 = 0 0 + -1r = 0 + 3 -1r = 0 + 3 Combine like terms: 0 + 3 = 3 -1r = 3 Divide each side by '-1'. r = -3 Simplifying r = -3

Subproblem 2

Set the factor '(5 + -1r)' equal to zero and attempt to solve: Simplifying 5 + -1r = 0 Solving 5 + -1r = 0 Move all terms containing r to the left, all other terms to the right. Add '-5' to each side of the equation. 5 + -5 + -1r = 0 + -5 Combine like terms: 5 + -5 = 0 0 + -1r = 0 + -5 -1r = 0 + -5 Combine like terms: 0 + -5 = -5 -1r = -5 Divide each side by '-1'. r = 5 Simplifying r = 5

Solution

r = {-3, 5}

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