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Simplifying
-9r2 + 121 = 0
Reorder the terms:
121 + -9r2 = 0
Solving
121 + -9r2 = 0
Solving for variable 'r'.
Move all terms containing r to the left, all other terms to the right.
Add '-121' to each side of the equation.
121 + -121 + -9r2 = 0 + -121
Combine like terms: 121 + -121 = 0
0 + -9r2 = 0 + -121
-9r2 = 0 + -121
Combine like terms: 0 + -121 = -121
-9r2 = -121
Divide each side by '-9'.
r2 = 13.44444444
Simplifying
r2 = 13.44444444
Take the square root of each side:
r = {-3.666666666, 3.666666666}
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