2x^2+13x-21=1

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Solution for 2x^2+13x-21=1 equation:


Simplifying
2x2 + 13x + -21 = 1

Reorder the terms:
-21 + 13x + 2x2 = 1

Solving
-21 + 13x + 2x2 = 1

Solving for variable 'x'.

Reorder the terms:
-21 + -1 + 13x + 2x2 = 1 + -1

Combine like terms: -21 + -1 = -22
-22 + 13x + 2x2 = 1 + -1

Combine like terms: 1 + -1 = 0
-22 + 13x + 2x2 = 0

Begin completing the square.  Divide all terms by
2 the coefficient of the squared term: 

Divide each side by '2'.
-11 + 6.5x + x2 = 0

Move the constant term to the right:

Add '11' to each side of the equation.
-11 + 6.5x + 11 + x2 = 0 + 11

Reorder the terms:
-11 + 11 + 6.5x + x2 = 0 + 11

Combine like terms: -11 + 11 = 0
0 + 6.5x + x2 = 0 + 11
6.5x + x2 = 0 + 11

Combine like terms: 0 + 11 = 11
6.5x + x2 = 11

The x term is 6.5x.  Take half its coefficient (3.25).
Square it (10.5625) and add it to both sides.

Add '10.5625' to each side of the equation.
6.5x + 10.5625 + x2 = 11 + 10.5625

Reorder the terms:
10.5625 + 6.5x + x2 = 11 + 10.5625

Combine like terms: 11 + 10.5625 = 21.5625
10.5625 + 6.5x + x2 = 21.5625

Factor a perfect square on the left side:
(x + 3.25)(x + 3.25) = 21.5625

Calculate the square root of the right side: 4.643543905

Break this problem into two subproblems by setting 
(x + 3.25) equal to 4.643543905 and -4.643543905.

Subproblem 1

x + 3.25 = 4.643543905 Simplifying x + 3.25 = 4.643543905 Reorder the terms: 3.25 + x = 4.643543905 Solving 3.25 + x = 4.643543905 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-3.25' to each side of the equation. 3.25 + -3.25 + x = 4.643543905 + -3.25 Combine like terms: 3.25 + -3.25 = 0.00 0.00 + x = 4.643543905 + -3.25 x = 4.643543905 + -3.25 Combine like terms: 4.643543905 + -3.25 = 1.393543905 x = 1.393543905 Simplifying x = 1.393543905

Subproblem 2

x + 3.25 = -4.643543905 Simplifying x + 3.25 = -4.643543905 Reorder the terms: 3.25 + x = -4.643543905 Solving 3.25 + x = -4.643543905 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-3.25' to each side of the equation. 3.25 + -3.25 + x = -4.643543905 + -3.25 Combine like terms: 3.25 + -3.25 = 0.00 0.00 + x = -4.643543905 + -3.25 x = -4.643543905 + -3.25 Combine like terms: -4.643543905 + -3.25 = -7.893543905 x = -7.893543905 Simplifying x = -7.893543905

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.393543905, -7.893543905}

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