3+2r-r^2=8

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Solution for 3+2r-r^2=8 equation:


Simplifying
3 + 2r + -1r2 = 8

Solving
3 + 2r + -1r2 = 8

Solving for variable 'r'.

Reorder the terms:
3 + -8 + 2r + -1r2 = 8 + -8

Combine like terms: 3 + -8 = -5
-5 + 2r + -1r2 = 8 + -8

Combine like terms: 8 + -8 = 0
-5 + 2r + -1r2 = 0

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
5 + -2r + r2 = 0

Move the constant term to the right:

Add '-5' to each side of the equation.
5 + -2r + -5 + r2 = 0 + -5

Reorder the terms:
5 + -5 + -2r + r2 = 0 + -5

Combine like terms: 5 + -5 = 0
0 + -2r + r2 = 0 + -5
-2r + r2 = 0 + -5

Combine like terms: 0 + -5 = -5
-2r + r2 = -5

The r term is -2r.  Take half its coefficient (-1).
Square it (1) and add it to both sides.

Add '1' to each side of the equation.
-2r + 1 + r2 = -5 + 1

Reorder the terms:
1 + -2r + r2 = -5 + 1

Combine like terms: -5 + 1 = -4
1 + -2r + r2 = -4

Factor a perfect square on the left side:
(r + -1)(r + -1) = -4

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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