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 = 111.25
90.25 + 19x + x2 = 111.25

Factor a perfect square on the left side:
(x + 9.5)(x + 9.5) = 111.25

Calculate the square root of the right side: 10.547511555

Break this problem into two subproblems by setting 
(x + 9.5) equal to 10.547511555 and -10.547511555.

Subproblem 1

x + 9.5 = 10.547511555 Simplifying x + 9.5 = 10.547511555 Reorder the terms: 9.5 + x = 10.547511555 Solving 9.5 + x = 10.547511555 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 = 10.547511555 + -9.5 Combine like terms: 9.5 + -9.5 = 0.0 0.0 + x = 10.547511555 + -9.5 x = 10.547511555 + -9.5 Combine like terms: 10.547511555 + -9.5 = 1.047511555 x = 1.047511555 Simplifying x = 1.047511555

Subproblem 2

x + 9.5 = -10.547511555 Simplifying x + 9.5 = -10.547511555 Reorder the terms: 9.5 + x = -10.547511555 Solving 9.5 + x = -10.547511555 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 = -10.547511555 + -9.5 Combine like terms: 9.5 + -9.5 = 0.0 0.0 + x = -10.547511555 + -9.5 x = -10.547511555 + -9.5 Combine like terms: -10.547511555 + -9.5 = -20.047511555 x = -20.047511555 Simplifying x = -20.047511555

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.047511555, -20.047511555}

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