9x^2+4x^2-18x-13=0

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Solution for 9x^2+4x^2-18x-13=0 equation:


Simplifying
9x2 + 4x2 + -18x + -13 = 0

Reorder the terms:
-13 + -18x + 9x2 + 4x2 = 0

Combine like terms: 9x2 + 4x2 = 13x2
-13 + -18x + 13x2 = 0

Solving
-13 + -18x + 13x2 = 0

Solving for variable 'x'.

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

Divide each side by '13'.
-1 + -1.384615385x + x2 = 0

Move the constant term to the right:

Add '1' to each side of the equation.
-1 + -1.384615385x + 1 + x2 = 0 + 1

Reorder the terms:
-1 + 1 + -1.384615385x + x2 = 0 + 1

Combine like terms: -1 + 1 = 0
0 + -1.384615385x + x2 = 0 + 1
-1.384615385x + x2 = 0 + 1

Combine like terms: 0 + 1 = 1
-1.384615385x + x2 = 1

The x term is -1.384615385x.  Take half its coefficient (-0.6923076925).
Square it (0.4792899411) and add it to both sides.

Add '0.4792899411' to each side of the equation.
-1.384615385x + 0.4792899411 + x2 = 1 + 0.4792899411

Reorder the terms:
0.4792899411 + -1.384615385x + x2 = 1 + 0.4792899411

Combine like terms: 1 + 0.4792899411 = 1.4792899411
0.4792899411 + -1.384615385x + x2 = 1.4792899411

Factor a perfect square on the left side:
(x + -0.6923076925)(x + -0.6923076925) = 1.4792899411

Calculate the square root of the right side: 1.216260639

Break this problem into two subproblems by setting 
(x + -0.6923076925) equal to 1.216260639 and -1.216260639.

Subproblem 1

x + -0.6923076925 = 1.216260639 Simplifying x + -0.6923076925 = 1.216260639 Reorder the terms: -0.6923076925 + x = 1.216260639 Solving -0.6923076925 + x = 1.216260639 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.6923076925' to each side of the equation. -0.6923076925 + 0.6923076925 + x = 1.216260639 + 0.6923076925 Combine like terms: -0.6923076925 + 0.6923076925 = 0.0000000000 0.0000000000 + x = 1.216260639 + 0.6923076925 x = 1.216260639 + 0.6923076925 Combine like terms: 1.216260639 + 0.6923076925 = 1.9085683315 x = 1.9085683315 Simplifying x = 1.9085683315

Subproblem 2

x + -0.6923076925 = -1.216260639 Simplifying x + -0.6923076925 = -1.216260639 Reorder the terms: -0.6923076925 + x = -1.216260639 Solving -0.6923076925 + x = -1.216260639 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.6923076925' to each side of the equation. -0.6923076925 + 0.6923076925 + x = -1.216260639 + 0.6923076925 Combine like terms: -0.6923076925 + 0.6923076925 = 0.0000000000 0.0000000000 + x = -1.216260639 + 0.6923076925 x = -1.216260639 + 0.6923076925 Combine like terms: -1.216260639 + 0.6923076925 = -0.5239529465 x = -0.5239529465 Simplifying x = -0.5239529465

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.9085683315, -0.5239529465}

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