Math help please
posted by Charlotte on .
1. The ordered pairs (1, 1), (2, 8), (3, 27), (4, 64), and (5,125) represent a function. What is a rule that represents this function?
Y = x
Y = 4x
Y = x^2
Y = x^3
I don't know how to solve this please help!

The easy way to do these is to look at it and try each of the answers.
For example, 2*1 is not 8 for a answer.
2*4 is 8 and that's ok but 3*4 is not 27.
For answer c, 2^2 = 4 and that's not ok.
Finally, 2*^3 = 8 which is ok. Next, 3^3 = 27 and that's ok. Next 4^3 = 64 and that's ok so I'd go with y = x^3. You can check out the last ordered pair to make sure 5^3 = 125. 
Well for this problem what you would do is you would take each set of ordered pairs and substitute the x coordinate for x and the y coordinate for y.
If for all 5 ordered pairs a function works, then that is your answer.
For example take the first one.
With the set of coordinates (1,1)...
the first function would work because 1=1.
Lets try substituting another pair for the same function. (2,8)
8=2.
Since that is not true, you know that this function is not true for all the ordered pairs.
Try this method for the rest of the functions. I hope this helps!