21x^2-40x-21=0

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Solution for 21x^2-40x-21=0 equation:


Simplifying
21x2 + -40x + -21 = 0

Reorder the terms:
-21 + -40x + 21x2 = 0

Solving
-21 + -40x + 21x2 = 0

Solving for variable 'x'.

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

Subproblem 1

Set the factor '(-3 + -7x)' equal to zero and attempt to solve: Simplifying -3 + -7x = 0 Solving -3 + -7x = 0 Move all terms containing x to the left, all other terms to the right. Add '3' to each side of the equation. -3 + 3 + -7x = 0 + 3 Combine like terms: -3 + 3 = 0 0 + -7x = 0 + 3 -7x = 0 + 3 Combine like terms: 0 + 3 = 3 -7x = 3 Divide each side by '-7'. x = -0.4285714286 Simplifying x = -0.4285714286

Subproblem 2

Set the factor '(7 + -3x)' equal to zero and attempt to solve: Simplifying 7 + -3x = 0 Solving 7 + -3x = 0 Move all terms containing x to the left, all other terms to the right. Add '-7' to each side of the equation. 7 + -7 + -3x = 0 + -7 Combine like terms: 7 + -7 = 0 0 + -3x = 0 + -7 -3x = 0 + -7 Combine like terms: 0 + -7 = -7 -3x = -7 Divide each side by '-3'. x = 2.333333333 Simplifying x = 2.333333333

Solution

x = {-0.4285714286, 2.333333333}

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