15x^2+8x+3=42

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Solution for 15x^2+8x+3=42 equation:


Simplifying
15x2 + 8x + 3 = 42

Reorder the terms:
3 + 8x + 15x2 = 42

Solving
3 + 8x + 15x2 = 42

Solving for variable 'x'.

Reorder the terms:
3 + -42 + 8x + 15x2 = 42 + -42

Combine like terms: 3 + -42 = -39
-39 + 8x + 15x2 = 42 + -42

Combine like terms: 42 + -42 = 0
-39 + 8x + 15x2 = 0

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

Divide each side by '15'.
-2.6 + 0.5333333333x + x2 = 0

Move the constant term to the right:

Add '2.6' to each side of the equation.
-2.6 + 0.5333333333x + 2.6 + x2 = 0 + 2.6

Reorder the terms:
-2.6 + 2.6 + 0.5333333333x + x2 = 0 + 2.6

Combine like terms: -2.6 + 2.6 = 0.0
0.0 + 0.5333333333x + x2 = 0 + 2.6
0.5333333333x + x2 = 0 + 2.6

Combine like terms: 0 + 2.6 = 2.6
0.5333333333x + x2 = 2.6

The x term is 0.5333333333x.  Take half its coefficient (0.2666666667).
Square it (0.07111111113) and add it to both sides.

Add '0.07111111113' to each side of the equation.
0.5333333333x + 0.07111111113 + x2 = 2.6 + 0.07111111113

Reorder the terms:
0.07111111113 + 0.5333333333x + x2 = 2.6 + 0.07111111113

Combine like terms: 2.6 + 0.07111111113 = 2.67111111113
0.07111111113 + 0.5333333333x + x2 = 2.67111111113

Factor a perfect square on the left side:
(x + 0.2666666667)(x + 0.2666666667) = 2.67111111113

Calculate the square root of the right side: 1.634353423

Break this problem into two subproblems by setting 
(x + 0.2666666667) equal to 1.634353423 and -1.634353423.

Subproblem 1

x + 0.2666666667 = 1.634353423 Simplifying x + 0.2666666667 = 1.634353423 Reorder the terms: 0.2666666667 + x = 1.634353423 Solving 0.2666666667 + x = 1.634353423 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.2666666667' to each side of the equation. 0.2666666667 + -0.2666666667 + x = 1.634353423 + -0.2666666667 Combine like terms: 0.2666666667 + -0.2666666667 = 0.0000000000 0.0000000000 + x = 1.634353423 + -0.2666666667 x = 1.634353423 + -0.2666666667 Combine like terms: 1.634353423 + -0.2666666667 = 1.3676867563 x = 1.3676867563 Simplifying x = 1.3676867563

Subproblem 2

x + 0.2666666667 = -1.634353423 Simplifying x + 0.2666666667 = -1.634353423 Reorder the terms: 0.2666666667 + x = -1.634353423 Solving 0.2666666667 + x = -1.634353423 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.2666666667' to each side of the equation. 0.2666666667 + -0.2666666667 + x = -1.634353423 + -0.2666666667 Combine like terms: 0.2666666667 + -0.2666666667 = 0.0000000000 0.0000000000 + x = -1.634353423 + -0.2666666667 x = -1.634353423 + -0.2666666667 Combine like terms: -1.634353423 + -0.2666666667 = -1.9010200897 x = -1.9010200897 Simplifying x = -1.9010200897

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.3676867563, -1.9010200897}

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