7-x^2=-84x

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Solution for 7-x^2=-84x equation:


Simplifying
7 + -1x2 = -84x

Solving
7 + -1x2 = -84x

Solving for variable 'x'.

Reorder the terms:
7 + 84x + -1x2 = -84x + 84x

Combine like terms: -84x + 84x = 0
7 + 84x + -1x2 = 0

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
-7 + -84x + x2 = 0

Move the constant term to the right:

Add '7' to each side of the equation.
-7 + -84x + 7 + x2 = 0 + 7

Reorder the terms:
-7 + 7 + -84x + x2 = 0 + 7

Combine like terms: -7 + 7 = 0
0 + -84x + x2 = 0 + 7
-84x + x2 = 0 + 7

Combine like terms: 0 + 7 = 7
-84x + x2 = 7

The x term is -84x.  Take half its coefficient (-42).
Square it (1764) and add it to both sides.

Add '1764' to each side of the equation.
-84x + 1764 + x2 = 7 + 1764

Reorder the terms:
1764 + -84x + x2 = 7 + 1764

Combine like terms: 7 + 1764 = 1771
1764 + -84x + x2 = 1771

Factor a perfect square on the left side:
(x + -42)(x + -42) = 1771

Calculate the square root of the right side: 42.083250825

Break this problem into two subproblems by setting 
(x + -42) equal to 42.083250825 and -42.083250825.

Subproblem 1

x + -42 = 42.083250825 Simplifying x + -42 = 42.083250825 Reorder the terms: -42 + x = 42.083250825 Solving -42 + x = 42.083250825 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '42' to each side of the equation. -42 + 42 + x = 42.083250825 + 42 Combine like terms: -42 + 42 = 0 0 + x = 42.083250825 + 42 x = 42.083250825 + 42 Combine like terms: 42.083250825 + 42 = 84.083250825 x = 84.083250825 Simplifying x = 84.083250825

Subproblem 2

x + -42 = -42.083250825 Simplifying x + -42 = -42.083250825 Reorder the terms: -42 + x = -42.083250825 Solving -42 + x = -42.083250825 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '42' to each side of the equation. -42 + 42 + x = -42.083250825 + 42 Combine like terms: -42 + 42 = 0 0 + x = -42.083250825 + 42 x = -42.083250825 + 42 Combine like terms: -42.083250825 + 42 = -0.083250825 x = -0.083250825 Simplifying x = -0.083250825

Solution

The solution to the problem is based on the solutions from the subproblems. x = {84.083250825, -0.083250825}

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