u^2+18u+20=0

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Solution for u^2+18u+20=0 equation:


Simplifying
u2 + 18u + 20 = 0

Reorder the terms:
20 + 18u + u2 = 0

Solving
20 + 18u + u2 = 0

Solving for variable 'u'.

Begin completing the square.

Move the constant term to the right:

Add '-20' to each side of the equation.
20 + 18u + -20 + u2 = 0 + -20

Reorder the terms:
20 + -20 + 18u + u2 = 0 + -20

Combine like terms: 20 + -20 = 0
0 + 18u + u2 = 0 + -20
18u + u2 = 0 + -20

Combine like terms: 0 + -20 = -20
18u + u2 = -20

The u term is 18u.  Take half its coefficient (9).
Square it (81) and add it to both sides.

Add '81' to each side of the equation.
18u + 81 + u2 = -20 + 81

Reorder the terms:
81 + 18u + u2 = -20 + 81

Combine like terms: -20 + 81 = 61
81 + 18u + u2 = 61

Factor a perfect square on the left side:
(u + 9)(u + 9) = 61

Calculate the square root of the right side: 7.810249676

Break this problem into two subproblems by setting 
(u + 9) equal to 7.810249676 and -7.810249676.

Subproblem 1

u + 9 = 7.810249676 Simplifying u + 9 = 7.810249676 Reorder the terms: 9 + u = 7.810249676 Solving 9 + u = 7.810249676 Solving for variable 'u'. Move all terms containing u to the left, all other terms to the right. Add '-9' to each side of the equation. 9 + -9 + u = 7.810249676 + -9 Combine like terms: 9 + -9 = 0 0 + u = 7.810249676 + -9 u = 7.810249676 + -9 Combine like terms: 7.810249676 + -9 = -1.189750324 u = -1.189750324 Simplifying u = -1.189750324

Subproblem 2

u + 9 = -7.810249676 Simplifying u + 9 = -7.810249676 Reorder the terms: 9 + u = -7.810249676 Solving 9 + u = -7.810249676 Solving for variable 'u'. Move all terms containing u to the left, all other terms to the right. Add '-9' to each side of the equation. 9 + -9 + u = -7.810249676 + -9 Combine like terms: 9 + -9 = 0 0 + u = -7.810249676 + -9 u = -7.810249676 + -9 Combine like terms: -7.810249676 + -9 = -16.810249676 u = -16.810249676 Simplifying u = -16.810249676

Solution

The solution to the problem is based on the solutions from the subproblems. u = {-1.189750324, -16.810249676}

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