3x^2+5x-40=0

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Solution for 3x^2+5x-40=0 equation:


Simplifying
3x2 + 5x + -40 = 0

Reorder the terms:
-40 + 5x + 3x2 = 0

Solving
-40 + 5x + 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'.
-13.33333333 + 1.666666667x + x2 = 0

Move the constant term to the right:

Add '13.33333333' to each side of the equation.
-13.33333333 + 1.666666667x + 13.33333333 + x2 = 0 + 13.33333333

Reorder the terms:
-13.33333333 + 13.33333333 + 1.666666667x + x2 = 0 + 13.33333333

Combine like terms: -13.33333333 + 13.33333333 = 0.00000000
0.00000000 + 1.666666667x + x2 = 0 + 13.33333333
1.666666667x + x2 = 0 + 13.33333333

Combine like terms: 0 + 13.33333333 = 13.33333333
1.666666667x + x2 = 13.33333333

The x term is 1.666666667x.  Take half its coefficient (0.8333333335).
Square it (0.6944444447) and add it to both sides.

Add '0.6944444447' to each side of the equation.
1.666666667x + 0.6944444447 + x2 = 13.33333333 + 0.6944444447

Reorder the terms:
0.6944444447 + 1.666666667x + x2 = 13.33333333 + 0.6944444447

Combine like terms: 13.33333333 + 0.6944444447 = 14.0277777747
0.6944444447 + 1.666666667x + x2 = 14.0277777747

Factor a perfect square on the left side:
(x + 0.8333333335)(x + 0.8333333335) = 14.0277777747

Calculate the square root of the right side: 3.745367509

Break this problem into two subproblems by setting 
(x + 0.8333333335) equal to 3.745367509 and -3.745367509.

Subproblem 1

x + 0.8333333335 = 3.745367509 Simplifying x + 0.8333333335 = 3.745367509 Reorder the terms: 0.8333333335 + x = 3.745367509 Solving 0.8333333335 + x = 3.745367509 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.8333333335' to each side of the equation. 0.8333333335 + -0.8333333335 + x = 3.745367509 + -0.8333333335 Combine like terms: 0.8333333335 + -0.8333333335 = 0.0000000000 0.0000000000 + x = 3.745367509 + -0.8333333335 x = 3.745367509 + -0.8333333335 Combine like terms: 3.745367509 + -0.8333333335 = 2.9120341755 x = 2.9120341755 Simplifying x = 2.9120341755

Subproblem 2

x + 0.8333333335 = -3.745367509 Simplifying x + 0.8333333335 = -3.745367509 Reorder the terms: 0.8333333335 + x = -3.745367509 Solving 0.8333333335 + x = -3.745367509 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.8333333335' to each side of the equation. 0.8333333335 + -0.8333333335 + x = -3.745367509 + -0.8333333335 Combine like terms: 0.8333333335 + -0.8333333335 = 0.0000000000 0.0000000000 + x = -3.745367509 + -0.8333333335 x = -3.745367509 + -0.8333333335 Combine like terms: -3.745367509 + -0.8333333335 = -4.5787008425 x = -4.5787008425 Simplifying x = -4.5787008425

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.9120341755, -4.5787008425}

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