2r^2+3=21

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Solution for 2r^2+3=21 equation: 


Simplifying
2r2 + 3 = 21

Reorder the terms:
3 + 2r2 = 21

Solving
3 + 2r2 = 21

Solving for variable 'r'.

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

Add '-3' to each side of the equation.
3 + -3 + 2r2 = 21 + -3

Combine like terms: 3 + -3 = 0
0 + 2r2 = 21 + -3
2r2 = 21 + -3

Combine like terms: 21 + -3 = 18
2r2 = 18

Divide each side by '2'.
r2 = 9

Simplifying
r2 = 9

Take the square root of each side:
r = {-3, 3}

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