6r^2-14r-15=0

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Solution for 6r^2-14r-15=0 equation:


Simplifying
6r2 + -14r + -15 = 0

Reorder the terms:
-15 + -14r + 6r2 = 0

Solving
-15 + -14r + 6r2 = 0

Solving for variable 'r'.

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

Divide each side by '6'.
-2.5 + -2.333333333r + r2 = 0

Move the constant term to the right:

Add '2.5' to each side of the equation.
-2.5 + -2.333333333r + 2.5 + r2 = 0 + 2.5

Reorder the terms:
-2.5 + 2.5 + -2.333333333r + r2 = 0 + 2.5

Combine like terms: -2.5 + 2.5 = 0.0
0.0 + -2.333333333r + r2 = 0 + 2.5
-2.333333333r + r2 = 0 + 2.5

Combine like terms: 0 + 2.5 = 2.5
-2.333333333r + r2 = 2.5

The r term is -2.333333333r.  Take half its coefficient (-1.166666667).
Square it (1.361111112) and add it to both sides.

Add '1.361111112' to each side of the equation.
-2.333333333r + 1.361111112 + r2 = 2.5 + 1.361111112

Reorder the terms:
1.361111112 + -2.333333333r + r2 = 2.5 + 1.361111112

Combine like terms: 2.5 + 1.361111112 = 3.861111112
1.361111112 + -2.333333333r + r2 = 3.861111112

Factor a perfect square on the left side:
(r + -1.166666667)(r + -1.166666667) = 3.861111112

Calculate the square root of the right side: 1.964971021

Break this problem into two subproblems by setting 
(r + -1.166666667) equal to 1.964971021 and -1.964971021.

Subproblem 1

r + -1.166666667 = 1.964971021 Simplifying r + -1.166666667 = 1.964971021 Reorder the terms: -1.166666667 + r = 1.964971021 Solving -1.166666667 + r = 1.964971021 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '1.166666667' to each side of the equation. -1.166666667 + 1.166666667 + r = 1.964971021 + 1.166666667 Combine like terms: -1.166666667 + 1.166666667 = 0.000000000 0.000000000 + r = 1.964971021 + 1.166666667 r = 1.964971021 + 1.166666667 Combine like terms: 1.964971021 + 1.166666667 = 3.131637688 r = 3.131637688 Simplifying r = 3.131637688

Subproblem 2

r + -1.166666667 = -1.964971021 Simplifying r + -1.166666667 = -1.964971021 Reorder the terms: -1.166666667 + r = -1.964971021 Solving -1.166666667 + r = -1.964971021 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '1.166666667' to each side of the equation. -1.166666667 + 1.166666667 + r = -1.964971021 + 1.166666667 Combine like terms: -1.166666667 + 1.166666667 = 0.000000000 0.000000000 + r = -1.964971021 + 1.166666667 r = -1.964971021 + 1.166666667 Combine like terms: -1.964971021 + 1.166666667 = -0.798304354 r = -0.798304354 Simplifying r = -0.798304354

Solution

The solution to the problem is based on the solutions from the subproblems. r = {3.131637688, -0.798304354}

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