2x^2+15x-3=42

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Solution for 2x^2+15x-3=42 equation:


Simplifying
2x2 + 15x + -3 = 42

Reorder the terms:
-3 + 15x + 2x2 = 42

Solving
-3 + 15x + 2x2 = 42

Solving for variable 'x'.

Reorder the terms:
-3 + -42 + 15x + 2x2 = 42 + -42

Combine like terms: -3 + -42 = -45
-45 + 15x + 2x2 = 42 + -42

Combine like terms: 42 + -42 = 0
-45 + 15x + 2x2 = 0

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

Divide each side by '2'.
-22.5 + 7.5x + x2 = 0

Move the constant term to the right:

Add '22.5' to each side of the equation.
-22.5 + 7.5x + 22.5 + x2 = 0 + 22.5

Reorder the terms:
-22.5 + 22.5 + 7.5x + x2 = 0 + 22.5

Combine like terms: -22.5 + 22.5 = 0.0
0.0 + 7.5x + x2 = 0 + 22.5
7.5x + x2 = 0 + 22.5

Combine like terms: 0 + 22.5 = 22.5
7.5x + x2 = 22.5

The x term is 7.5x.  Take half its coefficient (3.75).
Square it (14.0625) and add it to both sides.

Add '14.0625' to each side of the equation.
7.5x + 14.0625 + x2 = 22.5 + 14.0625

Reorder the terms:
14.0625 + 7.5x + x2 = 22.5 + 14.0625

Combine like terms: 22.5 + 14.0625 = 36.5625
14.0625 + 7.5x + x2 = 36.5625

Factor a perfect square on the left side:
(x + 3.75)(x + 3.75) = 36.5625

Calculate the square root of the right side: 6.046693311

Break this problem into two subproblems by setting 
(x + 3.75) equal to 6.046693311 and -6.046693311.

Subproblem 1

x + 3.75 = 6.046693311 Simplifying x + 3.75 = 6.046693311 Reorder the terms: 3.75 + x = 6.046693311 Solving 3.75 + x = 6.046693311 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-3.75' to each side of the equation. 3.75 + -3.75 + x = 6.046693311 + -3.75 Combine like terms: 3.75 + -3.75 = 0.00 0.00 + x = 6.046693311 + -3.75 x = 6.046693311 + -3.75 Combine like terms: 6.046693311 + -3.75 = 2.296693311 x = 2.296693311 Simplifying x = 2.296693311

Subproblem 2

x + 3.75 = -6.046693311 Simplifying x + 3.75 = -6.046693311 Reorder the terms: 3.75 + x = -6.046693311 Solving 3.75 + x = -6.046693311 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-3.75' to each side of the equation. 3.75 + -3.75 + x = -6.046693311 + -3.75 Combine like terms: 3.75 + -3.75 = 0.00 0.00 + x = -6.046693311 + -3.75 x = -6.046693311 + -3.75 Combine like terms: -6.046693311 + -3.75 = -9.796693311 x = -9.796693311 Simplifying x = -9.796693311

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.296693311, -9.796693311}

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