I am doing some functions review but I forget how to determin if it is a relation when given an equation
help me please!!

y=-3x +5

y=square root of (3x - 1)

Don't quite understand what you want here...

the relation is a function if when graphed it passes the vertical line test aka no two points have the same x value

An equation represents a function if for any in the function's domain there is preciely one value of that emerges. If there is more than 1 possible value of for any , then the equation is not a function.

Example: consider the equation . The domain for is . For any , there is only one value of that comes out of the equation. For example y(2) = 4, y(-10) = -20, etc. Therefore is a function.

Another example: consider . Here is in the domain . For equals zero there is one value of : zero. But for any positive there are two values of , since the square root of a positive number number is either plus or minus. For example, . Hence is not a function.

Hope this helps.

You mean that functions are the equations having an inverse, that is, are one one? Ok, but I thought that all equations could be represented as functions, but some of which had inverse, and others don't. K, thanks for the specification ebaines.

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Originally Posted by Unknown008

You mean that functions are the equations having an inverse, that is, are one one? .

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Not quite. Consider the equation f(x)= sin(x). This is defintely a fuction since for any value of x there is precisely one value of f(x). Its inverse is g(x) = arcsin(x), which is not a function, as for any value of x there are an infinite number of values for g(x), for example arcsin(0) = 0, pi, 2*pi, 3*pi, etc.

Oh, OK, thanks then, your really a help ebaines. Btw, my school is ebene, having the same pronunciation as your username, tee hee!