f := x -> x sin(2.2 x) - 5 sin(x) x sin(2.2 x) - 5 sin(x) NMf := x -> x - ---------------------------------------- sin(2.2 x) + 2.2 x cos(2.2 x) - 5 cos(x) 18.000000000000000000 19.368113045219229254 26.353190409602634801 23.502860797695800507 19.960984068175941358 20.101628877680130895 20.100303814440213602 20.100304112490147440 20.100304112490162322 <<< 8th iteration - not the closest root 20.100304112490162322