x^2-40=7x

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Solution for x^2-40=7x equation:


Simplifying
x2 + -40 = 7x

Reorder the terms:
-40 + x2 = 7x

Solving
-40 + x2 = 7x

Solving for variable 'x'.

Reorder the terms:
-40 + -7x + x2 = 7x + -7x

Combine like terms: 7x + -7x = 0
-40 + -7x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '40' to each side of the equation.
-40 + -7x + 40 + x2 = 0 + 40

Reorder the terms:
-40 + 40 + -7x + x2 = 0 + 40

Combine like terms: -40 + 40 = 0
0 + -7x + x2 = 0 + 40
-7x + x2 = 0 + 40

Combine like terms: 0 + 40 = 40
-7x + x2 = 40

The x term is -7x.  Take half its coefficient (-3.5).
Square it (12.25) and add it to both sides.

Add '12.25' to each side of the equation.
-7x + 12.25 + x2 = 40 + 12.25

Reorder the terms:
12.25 + -7x + x2 = 40 + 12.25

Combine like terms: 40 + 12.25 = 52.25
12.25 + -7x + x2 = 52.25

Factor a perfect square on the left side:
(x + -3.5)(x + -3.5) = 52.25

Calculate the square root of the right side: 7.228416147

Break this problem into two subproblems by setting 
(x + -3.5) equal to 7.228416147 and -7.228416147.

Subproblem 1

x + -3.5 = 7.228416147 Simplifying x + -3.5 = 7.228416147 Reorder the terms: -3.5 + x = 7.228416147 Solving -3.5 + x = 7.228416147 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3.5' to each side of the equation. -3.5 + 3.5 + x = 7.228416147 + 3.5 Combine like terms: -3.5 + 3.5 = 0.0 0.0 + x = 7.228416147 + 3.5 x = 7.228416147 + 3.5 Combine like terms: 7.228416147 + 3.5 = 10.728416147 x = 10.728416147 Simplifying x = 10.728416147

Subproblem 2

x + -3.5 = -7.228416147 Simplifying x + -3.5 = -7.228416147 Reorder the terms: -3.5 + x = -7.228416147 Solving -3.5 + x = -7.228416147 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3.5' to each side of the equation. -3.5 + 3.5 + x = -7.228416147 + 3.5 Combine like terms: -3.5 + 3.5 = 0.0 0.0 + x = -7.228416147 + 3.5 x = -7.228416147 + 3.5 Combine like terms: -7.228416147 + 3.5 = -3.728416147 x = -3.728416147 Simplifying x = -3.728416147

Solution

The solution to the problem is based on the solutions from the subproblems. x = {10.728416147, -3.728416147}

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