talking infront of a mic in a formal ceremony? or writing in bahasa melayu exam, then use hendak..when speaking to a random guy on a walk or to your friend just use nak... when talk to an indonesian use mahu..we malaysian seldom use mahu unless you are expressing a desire... saya mahukan kamu...i want you... saya mahu kamu semua dengar saya sekarang...i want all of you listen to me now..

--> Same meaning (Want) * mahu (formal) * hendak (common used) * nak (shortform of hendak)

nak is the shortform of hendak. In daily conversation we love to use shortform, so we use nak. . I want to eat. Saya nak makan. . Mahu is same meaning but we use nak more than mahu. . But it's good for u to know many meaning... bcz different people have diff word that they love to use. ^_^