.3x^2-1.8x-8.1=0

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Solution for .3x^2-1.8x-8.1=0 equation:


Simplifying
0.3x2 + -1.8x + -8.1 = 0

Reorder the terms:
-8.1 + -1.8x + 0.3x2 = 0

Solving
-8.1 + -1.8x + 0.3x2 = 0

Solving for variable 'x'.

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

Divide each side by '0.3'.
-27 + -6x + x2 = 0

Move the constant term to the right:

Add '27' to each side of the equation.
-27 + -6x + 27 + x2 = 0 + 27

Reorder the terms:
-27 + 27 + -6x + x2 = 0 + 27

Combine like terms: -27 + 27 = 0
0 + -6x + x2 = 0 + 27
-6x + x2 = 0 + 27

Combine like terms: 0 + 27 = 27
-6x + x2 = 27

The x term is -6x.  Take half its coefficient (-3).
Square it (9) and add it to both sides.

Add '9' to each side of the equation.
-6x + 9 + x2 = 27 + 9

Reorder the terms:
9 + -6x + x2 = 27 + 9

Combine like terms: 27 + 9 = 36
9 + -6x + x2 = 36

Factor a perfect square on the left side:
(x + -3)(x + -3) = 36

Calculate the square root of the right side: 6

Break this problem into two subproblems by setting 
(x + -3) equal to 6 and -6.

Subproblem 1

x + -3 = 6 Simplifying x + -3 = 6 Reorder the terms: -3 + x = 6 Solving -3 + x = 6 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3' to each side of the equation. -3 + 3 + x = 6 + 3 Combine like terms: -3 + 3 = 0 0 + x = 6 + 3 x = 6 + 3 Combine like terms: 6 + 3 = 9 x = 9 Simplifying x = 9

Subproblem 2

x + -3 = -6 Simplifying x + -3 = -6 Reorder the terms: -3 + x = -6 Solving -3 + x = -6 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3' to each side of the equation. -3 + 3 + x = -6 + 3 Combine like terms: -3 + 3 = 0 0 + x = -6 + 3 x = -6 + 3 Combine like terms: -6 + 3 = -3 x = -3 Simplifying x = -3

Solution

The solution to the problem is based on the solutions from the subproblems. x = {9, -3}

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