2r(5-r)=13+3r

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Solution for 2r(5-r)=13+3r equation:


Simplifying
2r(5 + -1r) = 13 + 3r
(5 * 2r + -1r * 2r) = 13 + 3r
(10r + -2r2) = 13 + 3r

Solving
10r + -2r2 = 13 + 3r

Solving for variable 'r'.

Reorder the terms:
-13 + 10r + -3r + -2r2 = 13 + 3r + -13 + -3r

Combine like terms: 10r + -3r = 7r
-13 + 7r + -2r2 = 13 + 3r + -13 + -3r

Reorder the terms:
-13 + 7r + -2r2 = 13 + -13 + 3r + -3r

Combine like terms: 13 + -13 = 0
-13 + 7r + -2r2 = 0 + 3r + -3r
-13 + 7r + -2r2 = 3r + -3r

Combine like terms: 3r + -3r = 0
-13 + 7r + -2r2 = 0

Begin completing the square.  Divide all terms by
-2 the coefficient of the squared term: 

Divide each side by '-2'.
6.5 + -3.5r + r2 = 0

Move the constant term to the right:

Add '-6.5' to each side of the equation.
6.5 + -3.5r + -6.5 + r2 = 0 + -6.5

Reorder the terms:
6.5 + -6.5 + -3.5r + r2 = 0 + -6.5

Combine like terms: 6.5 + -6.5 = 0.0
0.0 + -3.5r + r2 = 0 + -6.5
-3.5r + r2 = 0 + -6.5

Combine like terms: 0 + -6.5 = -6.5
-3.5r + r2 = -6.5

The r term is -3.5r.  Take half its coefficient (-1.75).
Square it (3.0625) and add it to both sides.

Add '3.0625' to each side of the equation.
-3.5r + 3.0625 + r2 = -6.5 + 3.0625

Reorder the terms:
3.0625 + -3.5r + r2 = -6.5 + 3.0625

Combine like terms: -6.5 + 3.0625 = -3.4375
3.0625 + -3.5r + r2 = -3.4375

Factor a perfect square on the left side:
(r + -1.75)(r + -1.75) = -3.4375

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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