0=5r^2-8r+7

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Solution for 0=5r^2-8r+7 equation:


Simplifying
0 = 5r2 + -8r + 7

Reorder the terms:
0 = 7 + -8r + 5r2

Solving
0 = 7 + -8r + 5r2

Solving for variable 'r'.

Combine like terms: 0 + -7 = -7
-7 + 8r + -5r2 = 7 + -8r + 5r2 + -7 + 8r + -5r2

Reorder the terms:
-7 + 8r + -5r2 = 7 + -7 + -8r + 8r + 5r2 + -5r2

Combine like terms: 7 + -7 = 0
-7 + 8r + -5r2 = 0 + -8r + 8r + 5r2 + -5r2
-7 + 8r + -5r2 = -8r + 8r + 5r2 + -5r2

Combine like terms: -8r + 8r = 0
-7 + 8r + -5r2 = 0 + 5r2 + -5r2
-7 + 8r + -5r2 = 5r2 + -5r2

Combine like terms: 5r2 + -5r2 = 0
-7 + 8r + -5r2 = 0

Begin completing the square.  Divide all terms by
-5 the coefficient of the squared term: 

Divide each side by '-5'.
1.4 + -1.6r + r2 = 0

Move the constant term to the right:

Add '-1.4' to each side of the equation.
1.4 + -1.6r + -1.4 + r2 = 0 + -1.4

Reorder the terms:
1.4 + -1.4 + -1.6r + r2 = 0 + -1.4

Combine like terms: 1.4 + -1.4 = 0.0
0.0 + -1.6r + r2 = 0 + -1.4
-1.6r + r2 = 0 + -1.4

Combine like terms: 0 + -1.4 = -1.4
-1.6r + r2 = -1.4

The r term is -1.6r.  Take half its coefficient (-0.8).
Square it (0.64) and add it to both sides.

Add '0.64' to each side of the equation.
-1.6r + 0.64 + r2 = -1.4 + 0.64

Reorder the terms:
0.64 + -1.6r + r2 = -1.4 + 0.64

Combine like terms: -1.4 + 0.64 = -0.76
0.64 + -1.6r + r2 = -0.76

Factor a perfect square on the left side:
(r + -0.8)(r + -0.8) = -0.76

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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