10 squared plus 18 squared equals C squared is the set up
After solving you should get 20.59
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f(0)=64, f(1)=66, f(2)=72, f(3)=82, f(4)=96,...=2,6,10,14,...=2{1,3,5,7,...}
This can be written 2{2x+1}, so the intervals on which f(x) increases are 4x+2.