-3x^2-9x+20=0

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Solution for -3x^2-9x+20=0 equation:


Simplifying
-3x2 + -9x + 20 = 0

Reorder the terms:
20 + -9x + -3x2 = 0

Solving
20 + -9x + -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'.
-6.666666667 + 3x + x2 = 0

Move the constant term to the right:

Add '6.666666667' to each side of the equation.
-6.666666667 + 3x + 6.666666667 + x2 = 0 + 6.666666667

Reorder the terms:
-6.666666667 + 6.666666667 + 3x + x2 = 0 + 6.666666667

Combine like terms: -6.666666667 + 6.666666667 = 0.000000000
0.000000000 + 3x + x2 = 0 + 6.666666667
3x + x2 = 0 + 6.666666667

Combine like terms: 0 + 6.666666667 = 6.666666667
3x + x2 = 6.666666667

The x term is 3x.  Take half its coefficient (1.5).
Square it (2.25) and add it to both sides.

Add '2.25' to each side of the equation.
3x + 2.25 + x2 = 6.666666667 + 2.25

Reorder the terms:
2.25 + 3x + x2 = 6.666666667 + 2.25

Combine like terms: 6.666666667 + 2.25 = 8.916666667
2.25 + 3x + x2 = 8.916666667

Factor a perfect square on the left side:
(x + 1.5)(x + 1.5) = 8.916666667

Calculate the square root of the right side: 2.986078811

Break this problem into two subproblems by setting 
(x + 1.5) equal to 2.986078811 and -2.986078811.

Subproblem 1

x + 1.5 = 2.986078811 Simplifying x + 1.5 = 2.986078811 Reorder the terms: 1.5 + x = 2.986078811 Solving 1.5 + x = 2.986078811 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.5' to each side of the equation. 1.5 + -1.5 + x = 2.986078811 + -1.5 Combine like terms: 1.5 + -1.5 = 0.0 0.0 + x = 2.986078811 + -1.5 x = 2.986078811 + -1.5 Combine like terms: 2.986078811 + -1.5 = 1.486078811 x = 1.486078811 Simplifying x = 1.486078811

Subproblem 2

x + 1.5 = -2.986078811 Simplifying x + 1.5 = -2.986078811 Reorder the terms: 1.5 + x = -2.986078811 Solving 1.5 + x = -2.986078811 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.5' to each side of the equation. 1.5 + -1.5 + x = -2.986078811 + -1.5 Combine like terms: 1.5 + -1.5 = 0.0 0.0 + x = -2.986078811 + -1.5 x = -2.986078811 + -1.5 Combine like terms: -2.986078811 + -1.5 = -4.486078811 x = -4.486078811 Simplifying x = -4.486078811

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.486078811, -4.486078811}

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