18x^2+7x-72=0

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Solution for 18x^2+7x-72=0 equation:


Simplifying
18x2 + 7x + -72 = 0

Reorder the terms:
-72 + 7x + 18x2 = 0

Solving
-72 + 7x + 18x2 = 0

Solving for variable 'x'.

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

Divide each side by '18'.
-4 + 0.3888888889x + x2 = 0

Move the constant term to the right:

Add '4' to each side of the equation.
-4 + 0.3888888889x + 4 + x2 = 0 + 4

Reorder the terms:
-4 + 4 + 0.3888888889x + x2 = 0 + 4

Combine like terms: -4 + 4 = 0
0 + 0.3888888889x + x2 = 0 + 4
0.3888888889x + x2 = 0 + 4

Combine like terms: 0 + 4 = 4
0.3888888889x + x2 = 4

The x term is 0.3888888889x.  Take half its coefficient (0.1944444445).
Square it (0.03780864200) and add it to both sides.

Add '0.03780864200' to each side of the equation.
0.3888888889x + 0.03780864200 + x2 = 4 + 0.03780864200

Reorder the terms:
0.03780864200 + 0.3888888889x + x2 = 4 + 0.03780864200

Combine like terms: 4 + 0.03780864200 = 4.037808642
0.03780864200 + 0.3888888889x + x2 = 4.037808642

Factor a perfect square on the left side:
(x + 0.1944444445)(x + 0.1944444445) = 4.037808642

Calculate the square root of the right side: 2.00942993

Break this problem into two subproblems by setting 
(x + 0.1944444445) equal to 2.00942993 and -2.00942993.

Subproblem 1

x + 0.1944444445 = 2.00942993 Simplifying x + 0.1944444445 = 2.00942993 Reorder the terms: 0.1944444445 + x = 2.00942993 Solving 0.1944444445 + x = 2.00942993 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.1944444445' to each side of the equation. 0.1944444445 + -0.1944444445 + x = 2.00942993 + -0.1944444445 Combine like terms: 0.1944444445 + -0.1944444445 = 0.0000000000 0.0000000000 + x = 2.00942993 + -0.1944444445 x = 2.00942993 + -0.1944444445 Combine like terms: 2.00942993 + -0.1944444445 = 1.8149854855 x = 1.8149854855 Simplifying x = 1.8149854855

Subproblem 2

x + 0.1944444445 = -2.00942993 Simplifying x + 0.1944444445 = -2.00942993 Reorder the terms: 0.1944444445 + x = -2.00942993 Solving 0.1944444445 + x = -2.00942993 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.1944444445' to each side of the equation. 0.1944444445 + -0.1944444445 + x = -2.00942993 + -0.1944444445 Combine like terms: 0.1944444445 + -0.1944444445 = 0.0000000000 0.0000000000 + x = -2.00942993 + -0.1944444445 x = -2.00942993 + -0.1944444445 Combine like terms: -2.00942993 + -0.1944444445 = -2.2038743745 x = -2.2038743745 Simplifying x = -2.2038743745

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.8149854855, -2.2038743745}

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