3x^2+7x-18=0

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Solution for 3x^2+7x-18=0 equation:


Simplifying
3x2 + 7x + -18 = 0

Reorder the terms:
-18 + 7x + 3x2 = 0

Solving
-18 + 7x + 3x2 = 0

Solving for variable 'x'.

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

Divide each side by '3'.
-6 + 2.333333333x + x2 = 0

Move the constant term to the right:

Add '6' to each side of the equation.
-6 + 2.333333333x + 6 + x2 = 0 + 6

Reorder the terms:
-6 + 6 + 2.333333333x + x2 = 0 + 6

Combine like terms: -6 + 6 = 0
0 + 2.333333333x + x2 = 0 + 6
2.333333333x + x2 = 0 + 6

Combine like terms: 0 + 6 = 6
2.333333333x + x2 = 6

The x term is 2.333333333x.  Take half its coefficient (1.166666667).
Square it (1.361111112) and add it to both sides.

Add '1.361111112' to each side of the equation.
2.333333333x + 1.361111112 + x2 = 6 + 1.361111112

Reorder the terms:
1.361111112 + 2.333333333x + x2 = 6 + 1.361111112

Combine like terms: 6 + 1.361111112 = 7.361111112
1.361111112 + 2.333333333x + x2 = 7.361111112

Factor a perfect square on the left side:
(x + 1.166666667)(x + 1.166666667) = 7.361111112

Calculate the square root of the right side: 2.713136766

Break this problem into two subproblems by setting 
(x + 1.166666667) equal to 2.713136766 and -2.713136766.

Subproblem 1

x + 1.166666667 = 2.713136766 Simplifying x + 1.166666667 = 2.713136766 Reorder the terms: 1.166666667 + x = 2.713136766 Solving 1.166666667 + x = 2.713136766 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.166666667' to each side of the equation. 1.166666667 + -1.166666667 + x = 2.713136766 + -1.166666667 Combine like terms: 1.166666667 + -1.166666667 = 0.000000000 0.000000000 + x = 2.713136766 + -1.166666667 x = 2.713136766 + -1.166666667 Combine like terms: 2.713136766 + -1.166666667 = 1.546470099 x = 1.546470099 Simplifying x = 1.546470099

Subproblem 2

x + 1.166666667 = -2.713136766 Simplifying x + 1.166666667 = -2.713136766 Reorder the terms: 1.166666667 + x = -2.713136766 Solving 1.166666667 + x = -2.713136766 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.166666667' to each side of the equation. 1.166666667 + -1.166666667 + x = -2.713136766 + -1.166666667 Combine like terms: 1.166666667 + -1.166666667 = 0.000000000 0.000000000 + x = -2.713136766 + -1.166666667 x = -2.713136766 + -1.166666667 Combine like terms: -2.713136766 + -1.166666667 = -3.879803433 x = -3.879803433 Simplifying x = -3.879803433

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.546470099, -3.879803433}

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