5x^2-11x-84=0

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Solution for 5x^2-11x-84=0 equation:


Simplifying
5x2 + -11x + -84 = 0

Reorder the terms:
-84 + -11x + 5x2 = 0

Solving
-84 + -11x + 5x2 = 0

Solving for variable 'x'.

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

Divide each side by '5'.
-16.8 + -2.2x + x2 = 0

Move the constant term to the right:

Add '16.8' to each side of the equation.
-16.8 + -2.2x + 16.8 + x2 = 0 + 16.8

Reorder the terms:
-16.8 + 16.8 + -2.2x + x2 = 0 + 16.8

Combine like terms: -16.8 + 16.8 = 0.0
0.0 + -2.2x + x2 = 0 + 16.8
-2.2x + x2 = 0 + 16.8

Combine like terms: 0 + 16.8 = 16.8
-2.2x + x2 = 16.8

The x term is -2.2x.  Take half its coefficient (-1.1).
Square it (1.21) and add it to both sides.

Add '1.21' to each side of the equation.
-2.2x + 1.21 + x2 = 16.8 + 1.21

Reorder the terms:
1.21 + -2.2x + x2 = 16.8 + 1.21

Combine like terms: 16.8 + 1.21 = 18.01
1.21 + -2.2x + x2 = 18.01

Factor a perfect square on the left side:
(x + -1.1)(x + -1.1) = 18.01

Calculate the square root of the right side: 4.243819035

Break this problem into two subproblems by setting 
(x + -1.1) equal to 4.243819035 and -4.243819035.

Subproblem 1

x + -1.1 = 4.243819035 Simplifying x + -1.1 = 4.243819035 Reorder the terms: -1.1 + x = 4.243819035 Solving -1.1 + x = 4.243819035 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1.1' to each side of the equation. -1.1 + 1.1 + x = 4.243819035 + 1.1 Combine like terms: -1.1 + 1.1 = 0.0 0.0 + x = 4.243819035 + 1.1 x = 4.243819035 + 1.1 Combine like terms: 4.243819035 + 1.1 = 5.343819035 x = 5.343819035 Simplifying x = 5.343819035

Subproblem 2

x + -1.1 = -4.243819035 Simplifying x + -1.1 = -4.243819035 Reorder the terms: -1.1 + x = -4.243819035 Solving -1.1 + x = -4.243819035 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1.1' to each side of the equation. -1.1 + 1.1 + x = -4.243819035 + 1.1 Combine like terms: -1.1 + 1.1 = 0.0 0.0 + x = -4.243819035 + 1.1 x = -4.243819035 + 1.1 Combine like terms: -4.243819035 + 1.1 = -3.143819035 x = -3.143819035 Simplifying x = -3.143819035

Solution

The solution to the problem is based on the solutions from the subproblems. x = {5.343819035, -3.143819035}

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