2r^2-10r-20=8

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Solution for 2r^2-10r-20=8 equation:


Simplifying
2r2 + -10r + -20 = 8

Reorder the terms:
-20 + -10r + 2r2 = 8

Solving
-20 + -10r + 2r2 = 8

Solving for variable 'r'.

Reorder the terms:
-20 + -8 + -10r + 2r2 = 8 + -8

Combine like terms: -20 + -8 = -28
-28 + -10r + 2r2 = 8 + -8

Combine like terms: 8 + -8 = 0
-28 + -10r + 2r2 = 0

Factor out the Greatest Common Factor (GCF), '2'.
2(-14 + -5r + r2) = 0

Factor a trinomial.
2((-2 + -1r)(7 + -1r)) = 0

Ignore the factor 2.

Subproblem 1

Set the factor '(-2 + -1r)' equal to zero and attempt to solve: Simplifying -2 + -1r = 0 Solving -2 + -1r = 0 Move all terms containing r to the left, all other terms to the right. Add '2' to each side of the equation. -2 + 2 + -1r = 0 + 2 Combine like terms: -2 + 2 = 0 0 + -1r = 0 + 2 -1r = 0 + 2 Combine like terms: 0 + 2 = 2 -1r = 2 Divide each side by '-1'. r = -2 Simplifying r = -2

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

Solution

r = {-2, 7}

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