198=3x^2+8x-42

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Solution for 198=3x^2+8x-42 equation:


Simplifying
198 = 3x2 + 8x + -42

Reorder the terms:
198 = -42 + 8x + 3x2

Solving
198 = -42 + 8x + 3x2

Solving for variable 'x'.

Combine like terms: 198 + 42 = 240
240 + -8x + -3x2 = -42 + 8x + 3x2 + 42 + -8x + -3x2

Reorder the terms:
240 + -8x + -3x2 = -42 + 42 + 8x + -8x + 3x2 + -3x2

Combine like terms: -42 + 42 = 0
240 + -8x + -3x2 = 0 + 8x + -8x + 3x2 + -3x2
240 + -8x + -3x2 = 8x + -8x + 3x2 + -3x2

Combine like terms: 8x + -8x = 0
240 + -8x + -3x2 = 0 + 3x2 + -3x2
240 + -8x + -3x2 = 3x2 + -3x2

Combine like terms: 3x2 + -3x2 = 0
240 + -8x + -3x2 = 0

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

Divide each side by '-3'.
-80 + 2.666666667x + x2 = 0

Move the constant term to the right:

Add '80' to each side of the equation.
-80 + 2.666666667x + 80 + x2 = 0 + 80

Reorder the terms:
-80 + 80 + 2.666666667x + x2 = 0 + 80

Combine like terms: -80 + 80 = 0
0 + 2.666666667x + x2 = 0 + 80
2.666666667x + x2 = 0 + 80

Combine like terms: 0 + 80 = 80
2.666666667x + x2 = 80

The x term is 2.666666667x.  Take half its coefficient (1.333333334).
Square it (1.777777780) and add it to both sides.

Add '1.777777780' to each side of the equation.
2.666666667x + 1.777777780 + x2 = 80 + 1.777777780

Reorder the terms:
1.777777780 + 2.666666667x + x2 = 80 + 1.777777780

Combine like terms: 80 + 1.777777780 = 81.77777778
1.777777780 + 2.666666667x + x2 = 81.77777778

Factor a perfect square on the left side:
(x + 1.333333334)(x + 1.333333334) = 81.77777778

Calculate the square root of the right side: 9.043106644

Break this problem into two subproblems by setting 
(x + 1.333333334) equal to 9.043106644 and -9.043106644.

Subproblem 1

x + 1.333333334 = 9.043106644 Simplifying x + 1.333333334 = 9.043106644 Reorder the terms: 1.333333334 + x = 9.043106644 Solving 1.333333334 + x = 9.043106644 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.333333334' to each side of the equation. 1.333333334 + -1.333333334 + x = 9.043106644 + -1.333333334 Combine like terms: 1.333333334 + -1.333333334 = 0.000000000 0.000000000 + x = 9.043106644 + -1.333333334 x = 9.043106644 + -1.333333334 Combine like terms: 9.043106644 + -1.333333334 = 7.70977331 x = 7.70977331 Simplifying x = 7.70977331

Subproblem 2

x + 1.333333334 = -9.043106644 Simplifying x + 1.333333334 = -9.043106644 Reorder the terms: 1.333333334 + x = -9.043106644 Solving 1.333333334 + x = -9.043106644 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.333333334' to each side of the equation. 1.333333334 + -1.333333334 + x = -9.043106644 + -1.333333334 Combine like terms: 1.333333334 + -1.333333334 = 0.000000000 0.000000000 + x = -9.043106644 + -1.333333334 x = -9.043106644 + -1.333333334 Combine like terms: -9.043106644 + -1.333333334 = -10.376439978 x = -10.376439978 Simplifying x = -10.376439978

Solution

The solution to the problem is based on the solutions from the subproblems. x = {7.70977331, -10.376439978}

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