21r^2+2r-40=0

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Solution for 21r^2+2r-40=0 equation:


Simplifying
21r2 + 2r + -40 = 0

Reorder the terms:
-40 + 2r + 21r2 = 0

Solving
-40 + 2r + 21r2 = 0

Solving for variable 'r'.

Factor a trinomial.
(-10 + -7r)(4 + -3r) = 0

Subproblem 1

Set the factor '(-10 + -7r)' equal to zero and attempt to solve: Simplifying -10 + -7r = 0 Solving -10 + -7r = 0 Move all terms containing r to the left, all other terms to the right. Add '10' to each side of the equation. -10 + 10 + -7r = 0 + 10 Combine like terms: -10 + 10 = 0 0 + -7r = 0 + 10 -7r = 0 + 10 Combine like terms: 0 + 10 = 10 -7r = 10 Divide each side by '-7'. r = -1.428571429 Simplifying r = -1.428571429

Subproblem 2

Set the factor '(4 + -3r)' equal to zero and attempt to solve: Simplifying 4 + -3r = 0 Solving 4 + -3r = 0 Move all terms containing r to the left, all other terms to the right. Add '-4' to each side of the equation. 4 + -4 + -3r = 0 + -4 Combine like terms: 4 + -4 = 0 0 + -3r = 0 + -4 -3r = 0 + -4 Combine like terms: 0 + -4 = -4 -3r = -4 Divide each side by '-3'. r = 1.333333333 Simplifying r = 1.333333333

Solution

r = {-1.428571429, 1.333333333}

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