-3b^2-11b=-15

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Solution for -3b^2-11b=-15 equation:


Simplifying
-3b2 + -11b = -15

Reorder the terms:
-11b + -3b2 = -15

Solving
-11b + -3b2 = -15

Solving for variable 'b'.

Reorder the terms:
15 + -11b + -3b2 = -15 + 15

Combine like terms: -15 + 15 = 0
15 + -11b + -3b2 = 0

Begin completing the square.  Divide all terms by
-3 the coefficient of the squared term: 

Divide each side by '-3'.
-5 + 3.666666667b + b2 = 0

Move the constant term to the right:

Add '5' to each side of the equation.
-5 + 3.666666667b + 5 + b2 = 0 + 5

Reorder the terms:
-5 + 5 + 3.666666667b + b2 = 0 + 5

Combine like terms: -5 + 5 = 0
0 + 3.666666667b + b2 = 0 + 5
3.666666667b + b2 = 0 + 5

Combine like terms: 0 + 5 = 5
3.666666667b + b2 = 5

The b term is 3.666666667b.  Take half its coefficient (1.833333334).
Square it (3.361111114) and add it to both sides.

Add '3.361111114' to each side of the equation.
3.666666667b + 3.361111114 + b2 = 5 + 3.361111114

Reorder the terms:
3.361111114 + 3.666666667b + b2 = 5 + 3.361111114

Combine like terms: 5 + 3.361111114 = 8.361111114
3.361111114 + 3.666666667b + b2 = 8.361111114

Factor a perfect square on the left side:
(b + 1.833333334)(b + 1.833333334) = 8.361111114

Calculate the square root of the right side: 2.891558596

Break this problem into two subproblems by setting 
(b + 1.833333334) equal to 2.891558596 and -2.891558596.

Subproblem 1

b + 1.833333334 = 2.891558596 Simplifying b + 1.833333334 = 2.891558596 Reorder the terms: 1.833333334 + b = 2.891558596 Solving 1.833333334 + b = 2.891558596 Solving for variable 'b'. Move all terms containing b to the left, all other terms to the right. Add '-1.833333334' to each side of the equation. 1.833333334 + -1.833333334 + b = 2.891558596 + -1.833333334 Combine like terms: 1.833333334 + -1.833333334 = 0.000000000 0.000000000 + b = 2.891558596 + -1.833333334 b = 2.891558596 + -1.833333334 Combine like terms: 2.891558596 + -1.833333334 = 1.058225262 b = 1.058225262 Simplifying b = 1.058225262

Subproblem 2

b + 1.833333334 = -2.891558596 Simplifying b + 1.833333334 = -2.891558596 Reorder the terms: 1.833333334 + b = -2.891558596 Solving 1.833333334 + b = -2.891558596 Solving for variable 'b'. Move all terms containing b to the left, all other terms to the right. Add '-1.833333334' to each side of the equation. 1.833333334 + -1.833333334 + b = -2.891558596 + -1.833333334 Combine like terms: 1.833333334 + -1.833333334 = 0.000000000 0.000000000 + b = -2.891558596 + -1.833333334 b = -2.891558596 + -1.833333334 Combine like terms: -2.891558596 + -1.833333334 = -4.72489193 b = -4.72489193 Simplifying b = -4.72489193

Solution

The solution to the problem is based on the solutions from the subproblems. b = {1.058225262, -4.72489193}

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