21r^2-20r+18=0

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Solution for 21r^2-20r+18=0 equation:


Simplifying
21r2 + -20r + 18 = 0

Reorder the terms:
18 + -20r + 21r2 = 0

Solving
18 + -20r + 21r2 = 0

Solving for variable 'r'.

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

Divide each side by '21'.
0.8571428571 + -0.9523809524r + r2 = 0

Move the constant term to the right:

Add '-0.8571428571' to each side of the equation.
0.8571428571 + -0.9523809524r + -0.8571428571 + r2 = 0 + -0.8571428571

Reorder the terms:
0.8571428571 + -0.8571428571 + -0.9523809524r + r2 = 0 + -0.8571428571

Combine like terms: 0.8571428571 + -0.8571428571 = 0.0000000000
0.0000000000 + -0.9523809524r + r2 = 0 + -0.8571428571
-0.9523809524r + r2 = 0 + -0.8571428571

Combine like terms: 0 + -0.8571428571 = -0.8571428571
-0.9523809524r + r2 = -0.8571428571

The r term is -0.9523809524r.  Take half its coefficient (-0.4761904762).
Square it (0.2267573696) and add it to both sides.

Add '0.2267573696' to each side of the equation.
-0.9523809524r + 0.2267573696 + r2 = -0.8571428571 + 0.2267573696

Reorder the terms:
0.2267573696 + -0.9523809524r + r2 = -0.8571428571 + 0.2267573696

Combine like terms: -0.8571428571 + 0.2267573696 = -0.6303854875
0.2267573696 + -0.9523809524r + r2 = -0.6303854875

Factor a perfect square on the left side:
(r + -0.4761904762)(r + -0.4761904762) = -0.6303854875

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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