x^2+21x-30=0

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Solution for x^2+21x-30=0 equation:


Simplifying
x2 + 21x + -30 = 0

Reorder the terms:
-30 + 21x + x2 = 0

Solving
-30 + 21x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '30' to each side of the equation.
-30 + 21x + 30 + x2 = 0 + 30

Reorder the terms:
-30 + 30 + 21x + x2 = 0 + 30

Combine like terms: -30 + 30 = 0
0 + 21x + x2 = 0 + 30
21x + x2 = 0 + 30

Combine like terms: 0 + 30 = 30
21x + x2 = 30

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 = 30 + 110.25

Reorder the terms:
110.25 + 21x + x2 = 30 + 110.25

Combine like terms: 30 + 110.25 = 140.25
110.25 + 21x + x2 = 140.25

Factor a perfect square on the left side:
(x + 10.5)(x + 10.5) = 140.25

Calculate the square root of the right side: 11.842719282

Break this problem into two subproblems by setting 
(x + 10.5) equal to 11.842719282 and -11.842719282.

Subproblem 1

x + 10.5 = 11.842719282 Simplifying x + 10.5 = 11.842719282 Reorder the terms: 10.5 + x = 11.842719282 Solving 10.5 + x = 11.842719282 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 = 11.842719282 + -10.5 Combine like terms: 10.5 + -10.5 = 0.0 0.0 + x = 11.842719282 + -10.5 x = 11.842719282 + -10.5 Combine like terms: 11.842719282 + -10.5 = 1.342719282 x = 1.342719282 Simplifying x = 1.342719282

Subproblem 2

x + 10.5 = -11.842719282 Simplifying x + 10.5 = -11.842719282 Reorder the terms: 10.5 + x = -11.842719282 Solving 10.5 + x = -11.842719282 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 = -11.842719282 + -10.5 Combine like terms: 10.5 + -10.5 = 0.0 0.0 + x = -11.842719282 + -10.5 x = -11.842719282 + -10.5 Combine like terms: -11.842719282 + -10.5 = -22.342719282 x = -22.342719282 Simplifying x = -22.342719282

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.342719282, -22.342719282}

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