" Are "f" and "g" both necessarily onto,if "g@f" is onto? "

Are f and g both necessarily onto, if gof is onto?

Are f and g both necessarily onto, if gof is onto?

Are f and g both necessarily onto,if gof is onto?

Are fand g both necessarily onto, if gof is onto?

Are f and g both necessarily onto, if gof is onto ?

Are f and g both necessarily onto, if gof is onto ?

Are f and g both necessarily onto, if gof is onto ?

Are f and g both necessarily onto, if gof is onto ?

Consider functions f and g such that composite gof is defined and is one one Are f and g both necessarily one-one.