x^2-19x+21=0

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Solution for x^2-19x+21=0 equation:


Simplifying
x2 + -19x + 21 = 0

Reorder the terms:
21 + -19x + x2 = 0

Solving
21 + -19x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '-21' to each side of the equation.
21 + -19x + -21 + x2 = 0 + -21

Reorder the terms:
21 + -21 + -19x + x2 = 0 + -21

Combine like terms: 21 + -21 = 0
0 + -19x + x2 = 0 + -21
-19x + x2 = 0 + -21

Combine like terms: 0 + -21 = -21
-19x + x2 = -21

The x term is -19x.  Take half its coefficient (-9.5).
Square it (90.25) and add it to both sides.

Add '90.25' to each side of the equation.
-19x + 90.25 + x2 = -21 + 90.25

Reorder the terms:
90.25 + -19x + x2 = -21 + 90.25

Combine like terms: -21 + 90.25 = 69.25
90.25 + -19x + x2 = 69.25

Factor a perfect square on the left side:
(x + -9.5)(x + -9.5) = 69.25

Calculate the square root of the right side: 8.321658489

Break this problem into two subproblems by setting 
(x + -9.5) equal to 8.321658489 and -8.321658489.

Subproblem 1

x + -9.5 = 8.321658489 Simplifying x + -9.5 = 8.321658489 Reorder the terms: -9.5 + x = 8.321658489 Solving -9.5 + x = 8.321658489 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '9.5' to each side of the equation. -9.5 + 9.5 + x = 8.321658489 + 9.5 Combine like terms: -9.5 + 9.5 = 0.0 0.0 + x = 8.321658489 + 9.5 x = 8.321658489 + 9.5 Combine like terms: 8.321658489 + 9.5 = 17.821658489 x = 17.821658489 Simplifying x = 17.821658489

Subproblem 2

x + -9.5 = -8.321658489 Simplifying x + -9.5 = -8.321658489 Reorder the terms: -9.5 + x = -8.321658489 Solving -9.5 + x = -8.321658489 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '9.5' to each side of the equation. -9.5 + 9.5 + x = -8.321658489 + 9.5 Combine like terms: -9.5 + 9.5 = 0.0 0.0 + x = -8.321658489 + 9.5 x = -8.321658489 + 9.5 Combine like terms: -8.321658489 + 9.5 = 1.178341511 x = 1.178341511 Simplifying x = 1.178341511

Solution

The solution to the problem is based on the solutions from the subproblems. x = {17.821658489, 1.178341511}

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