x^2-3x-4=40

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Solution for x^2-3x-4=40 equation:


Simplifying
x2 + -3x + -4 = 40

Reorder the terms:
-4 + -3x + x2 = 40

Solving
-4 + -3x + x2 = 40

Solving for variable 'x'.

Reorder the terms:
-4 + -40 + -3x + x2 = 40 + -40

Combine like terms: -4 + -40 = -44
-44 + -3x + x2 = 40 + -40

Combine like terms: 40 + -40 = 0
-44 + -3x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '44' to each side of the equation.
-44 + -3x + 44 + x2 = 0 + 44

Reorder the terms:
-44 + 44 + -3x + x2 = 0 + 44

Combine like terms: -44 + 44 = 0
0 + -3x + x2 = 0 + 44
-3x + x2 = 0 + 44

Combine like terms: 0 + 44 = 44
-3x + x2 = 44

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 = 44 + 2.25

Reorder the terms:
2.25 + -3x + x2 = 44 + 2.25

Combine like terms: 44 + 2.25 = 46.25
2.25 + -3x + x2 = 46.25

Factor a perfect square on the left side:
(x + -1.5)(x + -1.5) = 46.25

Calculate the square root of the right side: 6.800735254

Break this problem into two subproblems by setting 
(x + -1.5) equal to 6.800735254 and -6.800735254.

Subproblem 1

x + -1.5 = 6.800735254 Simplifying x + -1.5 = 6.800735254 Reorder the terms: -1.5 + x = 6.800735254 Solving -1.5 + x = 6.800735254 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 = 6.800735254 + 1.5 Combine like terms: -1.5 + 1.5 = 0.0 0.0 + x = 6.800735254 + 1.5 x = 6.800735254 + 1.5 Combine like terms: 6.800735254 + 1.5 = 8.300735254 x = 8.300735254 Simplifying x = 8.300735254

Subproblem 2

x + -1.5 = -6.800735254 Simplifying x + -1.5 = -6.800735254 Reorder the terms: -1.5 + x = -6.800735254 Solving -1.5 + x = -6.800735254 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 = -6.800735254 + 1.5 Combine like terms: -1.5 + 1.5 = 0.0 0.0 + x = -6.800735254 + 1.5 x = -6.800735254 + 1.5 Combine like terms: -6.800735254 + 1.5 = -5.300735254 x = -5.300735254 Simplifying x = -5.300735254

Solution

The solution to the problem is based on the solutions from the subproblems. x = {8.300735254, -5.300735254}

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