A function f from A to B is called onto if for all b in B there is an a in A such that f(a) = b. That is, all elements in B are used.

How do you prove a function is onto?

Mathematically, if the rule of assignment is in the form of a computation, then we need to solve the equation y=f(x) for x. If we can always express x in terms of y, and if the resulting x-value is in the domain, the function is onto.

What is the condition for onto function?

Onto function could be explained by considering two sets, Set A and Set B, which consist of elements. If for every element of B, there is at least one or more than one element matching with A, then the function is said to be onto function or surjective function. ... Therefore, it is an onto function.