r^2=-21-10r

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Solution for r^2=-21-10r equation:


Simplifying
r2 = -21 + -10r

Solving
r2 = -21 + -10r

Solving for variable 'r'.

Reorder the terms:
21 + 10r + r2 = -21 + -10r + 21 + 10r

Reorder the terms:
21 + 10r + r2 = -21 + 21 + -10r + 10r

Combine like terms: -21 + 21 = 0
21 + 10r + r2 = 0 + -10r + 10r
21 + 10r + r2 = -10r + 10r

Combine like terms: -10r + 10r = 0
21 + 10r + r2 = 0

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

Subproblem 1

Set the factor '(7 + r)' equal to zero and attempt to solve: Simplifying 7 + r = 0 Solving 7 + r = 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 + r = 0 + -7 Combine like terms: 7 + -7 = 0 0 + r = 0 + -7 r = 0 + -7 Combine like terms: 0 + -7 = -7 r = -7 Simplifying r = -7

Subproblem 2

Set the factor '(3 + r)' equal to zero and attempt to solve: Simplifying 3 + r = 0 Solving 3 + r = 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 + r = 0 + -3 Combine like terms: 3 + -3 = 0 0 + r = 0 + -3 r = 0 + -3 Combine like terms: 0 + -3 = -3 r = -3 Simplifying r = -3

Solution

r = {-7, -3}

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