b^2+20b=-90

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Solution for b^2+20b=-90 equation:


Simplifying
b2 + 20b = -90

Reorder the terms:
20b + b2 = -90

Solving
20b + b2 = -90

Solving for variable 'b'.

Reorder the terms:
90 + 20b + b2 = -90 + 90

Combine like terms: -90 + 90 = 0
90 + 20b + b2 = 0

Begin completing the square.

Move the constant term to the right:

Add '-90' to each side of the equation.
90 + 20b + -90 + b2 = 0 + -90

Reorder the terms:
90 + -90 + 20b + b2 = 0 + -90

Combine like terms: 90 + -90 = 0
0 + 20b + b2 = 0 + -90
20b + b2 = 0 + -90

Combine like terms: 0 + -90 = -90
20b + b2 = -90

The b term is 20b.  Take half its coefficient (10).
Square it (100) and add it to both sides.

Add '100' to each side of the equation.
20b + 100 + b2 = -90 + 100

Reorder the terms:
100 + 20b + b2 = -90 + 100

Combine like terms: -90 + 100 = 10
100 + 20b + b2 = 10

Factor a perfect square on the left side:
(b + 10)(b + 10) = 10

Calculate the square root of the right side: 3.16227766

Break this problem into two subproblems by setting 
(b + 10) equal to 3.16227766 and -3.16227766.

Subproblem 1

b + 10 = 3.16227766 Simplifying b + 10 = 3.16227766 Reorder the terms: 10 + b = 3.16227766 Solving 10 + b = 3.16227766 Solving for variable 'b'. Move all terms containing b to the left, all other terms to the right. Add '-10' to each side of the equation. 10 + -10 + b = 3.16227766 + -10 Combine like terms: 10 + -10 = 0 0 + b = 3.16227766 + -10 b = 3.16227766 + -10 Combine like terms: 3.16227766 + -10 = -6.83772234 b = -6.83772234 Simplifying b = -6.83772234

Subproblem 2

b + 10 = -3.16227766 Simplifying b + 10 = -3.16227766 Reorder the terms: 10 + b = -3.16227766 Solving 10 + b = -3.16227766 Solving for variable 'b'. Move all terms containing b to the left, all other terms to the right. Add '-10' to each side of the equation. 10 + -10 + b = -3.16227766 + -10 Combine like terms: 10 + -10 = 0 0 + b = -3.16227766 + -10 b = -3.16227766 + -10 Combine like terms: -3.16227766 + -10 = -13.16227766 b = -13.16227766 Simplifying b = -13.16227766

Solution

The solution to the problem is based on the solutions from the subproblems. b = {-6.83772234, -13.16227766}

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