3x^2-30x-40=0

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Solution for 3x^2-30x-40=0 equation:


Simplifying
3x2 + -30x + -40 = 0

Reorder the terms:
-40 + -30x + 3x2 = 0

Solving
-40 + -30x + 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 + -10x + x2 = 0

Move the constant term to the right:

Add '13.33333333' to each side of the equation.
-13.33333333 + -10x + 13.33333333 + x2 = 0 + 13.33333333

Reorder the terms:
-13.33333333 + 13.33333333 + -10x + x2 = 0 + 13.33333333

Combine like terms: -13.33333333 + 13.33333333 = 0.00000000
0.00000000 + -10x + x2 = 0 + 13.33333333
-10x + x2 = 0 + 13.33333333

Combine like terms: 0 + 13.33333333 = 13.33333333
-10x + x2 = 13.33333333

The x term is -10x.  Take half its coefficient (-5).
Square it (25) and add it to both sides.

Add '25' to each side of the equation.
-10x + 25 + x2 = 13.33333333 + 25

Reorder the terms:
25 + -10x + x2 = 13.33333333 + 25

Combine like terms: 13.33333333 + 25 = 38.33333333
25 + -10x + x2 = 38.33333333

Factor a perfect square on the left side:
(x + -5)(x + -5) = 38.33333333

Calculate the square root of the right side: 6.191391873

Break this problem into two subproblems by setting 
(x + -5) equal to 6.191391873 and -6.191391873.

Subproblem 1

x + -5 = 6.191391873 Simplifying x + -5 = 6.191391873 Reorder the terms: -5 + x = 6.191391873 Solving -5 + x = 6.191391873 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '5' to each side of the equation. -5 + 5 + x = 6.191391873 + 5 Combine like terms: -5 + 5 = 0 0 + x = 6.191391873 + 5 x = 6.191391873 + 5 Combine like terms: 6.191391873 + 5 = 11.191391873 x = 11.191391873 Simplifying x = 11.191391873

Subproblem 2

x + -5 = -6.191391873 Simplifying x + -5 = -6.191391873 Reorder the terms: -5 + x = -6.191391873 Solving -5 + x = -6.191391873 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '5' to each side of the equation. -5 + 5 + x = -6.191391873 + 5 Combine like terms: -5 + 5 = 0 0 + x = -6.191391873 + 5 x = -6.191391873 + 5 Combine like terms: -6.191391873 + 5 = -1.191391873 x = -1.191391873 Simplifying x = -1.191391873

Solution

The solution to the problem is based on the solutions from the subproblems. x = {11.191391873, -1.191391873}

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