Name: Cindy
Who is asking: Student
Level of the question: Secondary

Question: Create a table of values for each of the following functions: y=5x, y=52, and y=5x. I dont know to do this.

 

Hi Cindy.

A table of values is simply a matter of picking a few values of x and putting those values into the function to calculate the corresponding value of the function. You do it hoping to choose values of x where the function is doing something revealing. For example, I'll pick the function f(x) = 1/x and build a table of values for it:

x1/x
11
2.5
5.2
100.01
1000.001
1/22
1/1010
1/100100
0Undefined!
-1-1
-1/10-10
-1/100-100
-500-.002

These are enough values to give several co-ordinates to plot on a graph so you can see what the function is doing. If I picked just x values 1, 2, 3, 4, 5 then I might not realize that this function soars off to (positive) infinity as I get closer to zero on the positive side. The function is very close to zero and negative when I give it a large negative value of x. There's a vertical asymptote at x=0 - the value for which the function isn't defined.

Tables of values are pretty good tools for giving you a rough sketch, but if you don't choose good values of x, you might miss important details, so it's not a rigourous understanding of the function, but it is a good technique for getting oriented on a function and for double-checking later.

Hope this helps!
Stephen La Rocque>