x^2-21x-1000=0

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Solution for x^2-21x-1000=0 equation:


Simplifying
x2 + -21x + -1000 = 0

Reorder the terms:
-1000 + -21x + x2 = 0

Solving
-1000 + -21x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '1000' to each side of the equation.
-1000 + -21x + 1000 + x2 = 0 + 1000

Reorder the terms:
-1000 + 1000 + -21x + x2 = 0 + 1000

Combine like terms: -1000 + 1000 = 0
0 + -21x + x2 = 0 + 1000
-21x + x2 = 0 + 1000

Combine like terms: 0 + 1000 = 1000
-21x + x2 = 1000

The x term is -21x.  Take half its coefficient (-10.5).
Square it (110.25) and add it to both sides.

Add '110.25' to each side of the equation.
-21x + 110.25 + x2 = 1000 + 110.25

Reorder the terms:
110.25 + -21x + x2 = 1000 + 110.25

Combine like terms: 1000 + 110.25 = 1110.25
110.25 + -21x + x2 = 1110.25

Factor a perfect square on the left side:
(x + -10.5)(x + -10.5) = 1110.25

Calculate the square root of the right side: 33.320414163

Break this problem into two subproblems by setting 
(x + -10.5) equal to 33.320414163 and -33.320414163.

Subproblem 1

x + -10.5 = 33.320414163 Simplifying x + -10.5 = 33.320414163 Reorder the terms: -10.5 + x = 33.320414163 Solving -10.5 + x = 33.320414163 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '10.5' to each side of the equation. -10.5 + 10.5 + x = 33.320414163 + 10.5 Combine like terms: -10.5 + 10.5 = 0.0 0.0 + x = 33.320414163 + 10.5 x = 33.320414163 + 10.5 Combine like terms: 33.320414163 + 10.5 = 43.820414163 x = 43.820414163 Simplifying x = 43.820414163

Subproblem 2

x + -10.5 = -33.320414163 Simplifying x + -10.5 = -33.320414163 Reorder the terms: -10.5 + x = -33.320414163 Solving -10.5 + x = -33.320414163 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '10.5' to each side of the equation. -10.5 + 10.5 + x = -33.320414163 + 10.5 Combine like terms: -10.5 + 10.5 = 0.0 0.0 + x = -33.320414163 + 10.5 x = -33.320414163 + 10.5 Combine like terms: -33.320414163 + 10.5 = -22.820414163 x = -22.820414163 Simplifying x = -22.820414163

Solution

The solution to the problem is based on the solutions from the subproblems. x = {43.820414163, -22.820414163}

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