7x^2+3x-42=0

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Solution for 7x^2+3x-42=0 equation:


Simplifying
7x2 + 3x + -42 = 0

Reorder the terms:
-42 + 3x + 7x2 = 0

Solving
-42 + 3x + 7x2 = 0

Solving for variable 'x'.

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

Divide each side by '7'.
-6 + 0.4285714286x + x2 = 0

Move the constant term to the right:

Add '6' to each side of the equation.
-6 + 0.4285714286x + 6 + x2 = 0 + 6

Reorder the terms:
-6 + 6 + 0.4285714286x + x2 = 0 + 6

Combine like terms: -6 + 6 = 0
0 + 0.4285714286x + x2 = 0 + 6
0.4285714286x + x2 = 0 + 6

Combine like terms: 0 + 6 = 6
0.4285714286x + x2 = 6

The x term is 0.4285714286x.  Take half its coefficient (0.2142857143).
Square it (0.04591836735) and add it to both sides.

Add '0.04591836735' to each side of the equation.
0.4285714286x + 0.04591836735 + x2 = 6 + 0.04591836735

Reorder the terms:
0.04591836735 + 0.4285714286x + x2 = 6 + 0.04591836735

Combine like terms: 6 + 0.04591836735 = 6.04591836735
0.04591836735 + 0.4285714286x + x2 = 6.04591836735

Factor a perfect square on the left side:
(x + 0.2142857143)(x + 0.2142857143) = 6.04591836735

Calculate the square root of the right side: 2.458844925

Break this problem into two subproblems by setting 
(x + 0.2142857143) equal to 2.458844925 and -2.458844925.

Subproblem 1

x + 0.2142857143 = 2.458844925 Simplifying x + 0.2142857143 = 2.458844925 Reorder the terms: 0.2142857143 + x = 2.458844925 Solving 0.2142857143 + x = 2.458844925 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.2142857143' to each side of the equation. 0.2142857143 + -0.2142857143 + x = 2.458844925 + -0.2142857143 Combine like terms: 0.2142857143 + -0.2142857143 = 0.0000000000 0.0000000000 + x = 2.458844925 + -0.2142857143 x = 2.458844925 + -0.2142857143 Combine like terms: 2.458844925 + -0.2142857143 = 2.2445592107 x = 2.2445592107 Simplifying x = 2.2445592107

Subproblem 2

x + 0.2142857143 = -2.458844925 Simplifying x + 0.2142857143 = -2.458844925 Reorder the terms: 0.2142857143 + x = -2.458844925 Solving 0.2142857143 + x = -2.458844925 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.2142857143' to each side of the equation. 0.2142857143 + -0.2142857143 + x = -2.458844925 + -0.2142857143 Combine like terms: 0.2142857143 + -0.2142857143 = 0.0000000000 0.0000000000 + x = -2.458844925 + -0.2142857143 x = -2.458844925 + -0.2142857143 Combine like terms: -2.458844925 + -0.2142857143 = -2.6731306393 x = -2.6731306393 Simplifying x = -2.6731306393

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.2445592107, -2.6731306393}

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