4x^2-21=8x

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Solution for 4x^2-21=8x equation:


Simplifying
4x2 + -21 = 8x

Reorder the terms:
-21 + 4x2 = 8x

Solving
-21 + 4x2 = 8x

Solving for variable 'x'.

Reorder the terms:
-21 + -8x + 4x2 = 8x + -8x

Combine like terms: 8x + -8x = 0
-21 + -8x + 4x2 = 0

Factor a trinomial.
(-3 + -2x)(7 + -2x) = 0

Subproblem 1

Set the factor '(-3 + -2x)' equal to zero and attempt to solve: Simplifying -3 + -2x = 0 Solving -3 + -2x = 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 + -2x = 0 + 3 Combine like terms: -3 + 3 = 0 0 + -2x = 0 + 3 -2x = 0 + 3 Combine like terms: 0 + 3 = 3 -2x = 3 Divide each side by '-2'. x = -1.5 Simplifying x = -1.5

Subproblem 2

Set the factor '(7 + -2x)' equal to zero and attempt to solve: Simplifying 7 + -2x = 0 Solving 7 + -2x = 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 + -2x = 0 + -7 Combine like terms: 7 + -7 = 0 0 + -2x = 0 + -7 -2x = 0 + -7 Combine like terms: 0 + -7 = -7 -2x = -7 Divide each side by '-2'. x = 3.5 Simplifying x = 3.5

Solution

x = {-1.5, 3.5}

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