8r^2+56r+121=0

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Solution for 8r^2+56r+121=0 equation:


Simplifying
8r2 + 56r + 121 = 0

Reorder the terms:
121 + 56r + 8r2 = 0

Solving
121 + 56r + 8r2 = 0

Solving for variable 'r'.

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

Divide each side by '8'.
15.125 + 7r + r2 = 0

Move the constant term to the right:

Add '-15.125' to each side of the equation.
15.125 + 7r + -15.125 + r2 = 0 + -15.125

Reorder the terms:
15.125 + -15.125 + 7r + r2 = 0 + -15.125

Combine like terms: 15.125 + -15.125 = 0.000
0.000 + 7r + r2 = 0 + -15.125
7r + r2 = 0 + -15.125

Combine like terms: 0 + -15.125 = -15.125
7r + r2 = -15.125

The r term is 7r.  Take half its coefficient (3.5).
Square it (12.25) and add it to both sides.

Add '12.25' to each side of the equation.
7r + 12.25 + r2 = -15.125 + 12.25

Reorder the terms:
12.25 + 7r + r2 = -15.125 + 12.25

Combine like terms: -15.125 + 12.25 = -2.875
12.25 + 7r + r2 = -2.875

Factor a perfect square on the left side:
(r + 3.5)(r + 3.5) = -2.875

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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