21x^2-165x-216=0

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Solution for 21x^2-165x-216=0 equation:


Simplifying
21x2 + -165x + -216 = 0

Reorder the terms:
-216 + -165x + 21x2 = 0

Solving
-216 + -165x + 21x2 = 0

Solving for variable 'x'.

Factor out the Greatest Common Factor (GCF), '3'.
3(-72 + -55x + 7x2) = 0

Factor a trinomial.
3((-8 + -7x)(9 + -1x)) = 0

Ignore the factor 3.

Subproblem 1

Set the factor '(-8 + -7x)' equal to zero and attempt to solve: Simplifying -8 + -7x = 0 Solving -8 + -7x = 0 Move all terms containing x to the left, all other terms to the right. Add '8' to each side of the equation. -8 + 8 + -7x = 0 + 8 Combine like terms: -8 + 8 = 0 0 + -7x = 0 + 8 -7x = 0 + 8 Combine like terms: 0 + 8 = 8 -7x = 8 Divide each side by '-7'. x = -1.142857143 Simplifying x = -1.142857143

Subproblem 2

Set the factor '(9 + -1x)' equal to zero and attempt to solve: Simplifying 9 + -1x = 0 Solving 9 + -1x = 0 Move all terms containing x to the left, all other terms to the right. Add '-9' to each side of the equation. 9 + -9 + -1x = 0 + -9 Combine like terms: 9 + -9 = 0 0 + -1x = 0 + -9 -1x = 0 + -9 Combine like terms: 0 + -9 = -9 -1x = -9 Divide each side by '-1'. x = 9 Simplifying x = 9

Solution

x = {-1.142857143, 9}

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