3(x^2-5x)=20

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Solution for 3(x^2-5x)=20 equation:


Simplifying
3(x2 + -5x) = 20

Reorder the terms:
3(-5x + x2) = 20
(-5x * 3 + x2 * 3) = 20
(-15x + 3x2) = 20

Solving
-15x + 3x2 = 20

Solving for variable 'x'.

Reorder the terms:
-20 + -15x + 3x2 = 20 + -20

Combine like terms: 20 + -20 = 0
-20 + -15x + 3x2 = 0

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

Divide each side by '3'.
-6.666666667 + -5x + x2 = 0

Move the constant term to the right:

Add '6.666666667' to each side of the equation.
-6.666666667 + -5x + 6.666666667 + x2 = 0 + 6.666666667

Reorder the terms:
-6.666666667 + 6.666666667 + -5x + x2 = 0 + 6.666666667

Combine like terms: -6.666666667 + 6.666666667 = 0.000000000
0.000000000 + -5x + x2 = 0 + 6.666666667
-5x + x2 = 0 + 6.666666667

Combine like terms: 0 + 6.666666667 = 6.666666667
-5x + x2 = 6.666666667

The x term is -5x.  Take half its coefficient (-2.5).
Square it (6.25) and add it to both sides.

Add '6.25' to each side of the equation.
-5x + 6.25 + x2 = 6.666666667 + 6.25

Reorder the terms:
6.25 + -5x + x2 = 6.666666667 + 6.25

Combine like terms: 6.666666667 + 6.25 = 12.916666667
6.25 + -5x + x2 = 12.916666667

Factor a perfect square on the left side:
(x + -2.5)(x + -2.5) = 12.916666667

Calculate the square root of the right side: 3.593976442

Break this problem into two subproblems by setting 
(x + -2.5) equal to 3.593976442 and -3.593976442.

Subproblem 1

x + -2.5 = 3.593976442 Simplifying x + -2.5 = 3.593976442 Reorder the terms: -2.5 + x = 3.593976442 Solving -2.5 + x = 3.593976442 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2.5' to each side of the equation. -2.5 + 2.5 + x = 3.593976442 + 2.5 Combine like terms: -2.5 + 2.5 = 0.0 0.0 + x = 3.593976442 + 2.5 x = 3.593976442 + 2.5 Combine like terms: 3.593976442 + 2.5 = 6.093976442 x = 6.093976442 Simplifying x = 6.093976442

Subproblem 2

x + -2.5 = -3.593976442 Simplifying x + -2.5 = -3.593976442 Reorder the terms: -2.5 + x = -3.593976442 Solving -2.5 + x = -3.593976442 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2.5' to each side of the equation. -2.5 + 2.5 + x = -3.593976442 + 2.5 Combine like terms: -2.5 + 2.5 = 0.0 0.0 + x = -3.593976442 + 2.5 x = -3.593976442 + 2.5 Combine like terms: -3.593976442 + 2.5 = -1.093976442 x = -1.093976442 Simplifying x = -1.093976442

Solution

The solution to the problem is based on the solutions from the subproblems. x = {6.093976442, -1.093976442}

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