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HallsofIvy
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No, they have one y output for every x input! If you were specifically asked to graph the function [itex]y= \sqrt{x}[/itex] and graphed the entire parabola, yes you would be marked wrong. If you were asked to graph x= y2 (so y is a "relation", not a function of x, though now x is a function of y) then you should graph the entire parabola.lLovePhysics said:What's so important about functions anyways? All they have are two y outputs for every x input right? Would it make a big difference (and get marked wrong) if I drew a horizontal parabola rather than just the top half??
There is nothing terribly important about "functions" (except that they are somewhat simpler than "relations") in mathematics but they tend to be very important in applications of mathematics to science because of the requirement of "repeatability": if you do an experiment twice, with everything set up exactly the same way, you should get exactly the same result- one input, one output. "This causes that" gives functions.
Think of it this way: If you were to go to a store and find different products that had the same price, you would not be surprised, right? The "product" is not a function of the price. On the other hand, if you found exactly the same product, same size, brand, and everything, in the same store for two different prices, you would know that something was wrong: the price is a function of the product.