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Hello ^_^

I just have a few questions regarding onto functions. I'm a student studying BS Math here in the Phils. Right now i have a subject concerning math logic, and before we study the subject proper, my professor is discussing the basics of relations an functions ^_^;;; So if this question is misplaced Im truly sorry ^^;;;

In my previous quiz, there was a question that asked "State whether the given function is onto or not:

Domain = [-4,4], f(x) = x^2

Domain = [-1,1], f(x) = sin x

My understanding of an onto function is that it is a function wherein all the members of the codomain of the function should be assigned to at least one value of x in the domain. I answered that "yes, f(x)=x^2 is an onto function" because all the values of x in the domain have a corresponding y, i.e., there is no undefined value for any value of x or y. The next question's answer was was the same. However, when I asked for clarifications on what were the correct answers, my professor said that these two functions were not onto. Can someone please tell me why?

Thanx in advance ^_^

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# Questions about what is an onto function and what is not

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