2r^2-85=-7

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Solution for 2r^2-85=-7 equation:


Simplifying
2r2 + -85 = -7

Reorder the terms:
-85 + 2r2 = -7

Solving
-85 + 2r2 = -7

Solving for variable 'r'.

Move all terms containing r to the left, all other terms to the right.

Add '85' to each side of the equation.
-85 + 85 + 2r2 = -7 + 85

Combine like terms: -85 + 85 = 0
0 + 2r2 = -7 + 85
2r2 = -7 + 85

Combine like terms: -7 + 85 = 78
2r2 = 78

Divide each side by '2'.
r2 = 39

Simplifying
r2 = 39

Take the square root of each side:
r = {-6.244997998, 6.244997998}

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