5x^2-8x=21

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Solution for 5x^2-8x=21 equation:


Simplifying
5x2 + -8x = 21

Reorder the terms:
-8x + 5x2 = 21

Solving
-8x + 5x2 = 21

Solving for variable 'x'.

Reorder the terms:
-21 + -8x + 5x2 = 21 + -21

Combine like terms: 21 + -21 = 0
-21 + -8x + 5x2 = 0

Factor a trinomial.
(-7 + -5x)(3 + -1x) = 0

Subproblem 1

Set the factor '(-7 + -5x)' equal to zero and attempt to solve: Simplifying -7 + -5x = 0 Solving -7 + -5x = 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 + -5x = 0 + 7 Combine like terms: -7 + 7 = 0 0 + -5x = 0 + 7 -5x = 0 + 7 Combine like terms: 0 + 7 = 7 -5x = 7 Divide each side by '-5'. x = -1.4 Simplifying x = -1.4

Subproblem 2

Set the factor '(3 + -1x)' equal to zero and attempt to solve: Simplifying 3 + -1x = 0 Solving 3 + -1x = 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 + -1x = 0 + -3 Combine like terms: 3 + -3 = 0 0 + -1x = 0 + -3 -1x = 0 + -3 Combine like terms: 0 + -3 = -3 -1x = -3 Divide each side by '-1'. x = 3 Simplifying x = 3

Solution

x = {-1.4, 3}

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