-x^2+90x+99=0

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Solution for -x^2+90x+99=0 equation:


Simplifying
-1x2 + 90x + 99 = 0

Reorder the terms:
99 + 90x + -1x2 = 0

Solving
99 + 90x + -1x2 = 0

Solving for variable 'x'.

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

Divide each side by '-1'.
-99 + -90x + x2 = 0

Move the constant term to the right:

Add '99' to each side of the equation.
-99 + -90x + 99 + x2 = 0 + 99

Reorder the terms:
-99 + 99 + -90x + x2 = 0 + 99

Combine like terms: -99 + 99 = 0
0 + -90x + x2 = 0 + 99
-90x + x2 = 0 + 99

Combine like terms: 0 + 99 = 99
-90x + x2 = 99

The x term is -90x.  Take half its coefficient (-45).
Square it (2025) and add it to both sides.

Add '2025' to each side of the equation.
-90x + 2025 + x2 = 99 + 2025

Reorder the terms:
2025 + -90x + x2 = 99 + 2025

Combine like terms: 99 + 2025 = 2124
2025 + -90x + x2 = 2124

Factor a perfect square on the left side:
(x + -45)(x + -45) = 2124

Calculate the square root of the right side: 46.086874487

Break this problem into two subproblems by setting 
(x + -45) equal to 46.086874487 and -46.086874487.

Subproblem 1

x + -45 = 46.086874487 Simplifying x + -45 = 46.086874487 Reorder the terms: -45 + x = 46.086874487 Solving -45 + x = 46.086874487 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '45' to each side of the equation. -45 + 45 + x = 46.086874487 + 45 Combine like terms: -45 + 45 = 0 0 + x = 46.086874487 + 45 x = 46.086874487 + 45 Combine like terms: 46.086874487 + 45 = 91.086874487 x = 91.086874487 Simplifying x = 91.086874487

Subproblem 2

x + -45 = -46.086874487 Simplifying x + -45 = -46.086874487 Reorder the terms: -45 + x = -46.086874487 Solving -45 + x = -46.086874487 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '45' to each side of the equation. -45 + 45 + x = -46.086874487 + 45 Combine like terms: -45 + 45 = 0 0 + x = -46.086874487 + 45 x = -46.086874487 + 45 Combine like terms: -46.086874487 + 45 = -1.086874487 x = -1.086874487 Simplifying x = -1.086874487

Solution

The solution to the problem is based on the solutions from the subproblems. x = {91.086874487, -1.086874487}

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