7x^2+18x-11=0

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Solution for 7x^2+18x-11=0 equation:


Simplifying
7x2 + 18x + -11 = 0

Reorder the terms:
-11 + 18x + 7x2 = 0

Solving
-11 + 18x + 7x2 = 0

Solving for variable 'x'.

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

Divide each side by '7'.
-1.571428571 + 2.571428571x + x2 = 0

Move the constant term to the right:

Add '1.571428571' to each side of the equation.
-1.571428571 + 2.571428571x + 1.571428571 + x2 = 0 + 1.571428571

Reorder the terms:
-1.571428571 + 1.571428571 + 2.571428571x + x2 = 0 + 1.571428571

Combine like terms: -1.571428571 + 1.571428571 = 0.000000000
0.000000000 + 2.571428571x + x2 = 0 + 1.571428571
2.571428571x + x2 = 0 + 1.571428571

Combine like terms: 0 + 1.571428571 = 1.571428571
2.571428571x + x2 = 1.571428571

The x term is 2.571428571x.  Take half its coefficient (1.285714286).
Square it (1.653061225) and add it to both sides.

Add '1.653061225' to each side of the equation.
2.571428571x + 1.653061225 + x2 = 1.571428571 + 1.653061225

Reorder the terms:
1.653061225 + 2.571428571x + x2 = 1.571428571 + 1.653061225

Combine like terms: 1.571428571 + 1.653061225 = 3.224489796
1.653061225 + 2.571428571x + x2 = 3.224489796

Factor a perfect square on the left side:
(x + 1.285714286)(x + 1.285714286) = 3.224489796

Calculate the square root of the right side: 1.795686441

Break this problem into two subproblems by setting 
(x + 1.285714286) equal to 1.795686441 and -1.795686441.

Subproblem 1

x + 1.285714286 = 1.795686441 Simplifying x + 1.285714286 = 1.795686441 Reorder the terms: 1.285714286 + x = 1.795686441 Solving 1.285714286 + x = 1.795686441 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.285714286' to each side of the equation. 1.285714286 + -1.285714286 + x = 1.795686441 + -1.285714286 Combine like terms: 1.285714286 + -1.285714286 = 0.000000000 0.000000000 + x = 1.795686441 + -1.285714286 x = 1.795686441 + -1.285714286 Combine like terms: 1.795686441 + -1.285714286 = 0.509972155 x = 0.509972155 Simplifying x = 0.509972155

Subproblem 2

x + 1.285714286 = -1.795686441 Simplifying x + 1.285714286 = -1.795686441 Reorder the terms: 1.285714286 + x = -1.795686441 Solving 1.285714286 + x = -1.795686441 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.285714286' to each side of the equation. 1.285714286 + -1.285714286 + x = -1.795686441 + -1.285714286 Combine like terms: 1.285714286 + -1.285714286 = 0.000000000 0.000000000 + x = -1.795686441 + -1.285714286 x = -1.795686441 + -1.285714286 Combine like terms: -1.795686441 + -1.285714286 = -3.081400727 x = -3.081400727 Simplifying x = -3.081400727

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.509972155, -3.081400727}

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