21=2x^2-1(x)

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Solution for 21=2x^2-1(x) equation:


Simplifying
21 = 2x2 + -1(x)

Reorder the terms:
21 = -1x + 2x2

Solving
21 = -1x + 2x2

Solving for variable 'x'.

Reorder the terms:
21 + x + -2x2 = -1x + x + 2x2 + -2x2

Combine like terms: -1x + x = 0
21 + x + -2x2 = 0 + 2x2 + -2x2
21 + x + -2x2 = 2x2 + -2x2

Combine like terms: 2x2 + -2x2 = 0
21 + x + -2x2 = 0

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

Subproblem 1

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

Subproblem 2

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

Solution

x = {3.5, -3}

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