Question

Explain how the graph of y2is related to the graph of y1. y1=4/x and y2 = 9/x

Answer 1

Yes, that is the purpose for which it was intended but at A-level the first thing you're taught is the appropriate use of technology to 'enhance' mathematics and the limitations of calculators. Any curve no matter what kind can be plotted by first finding the x intercept by putting y = 0 and the y-intercept by placing x=0 and then using some small points to get the general shape. For something trivial as the equation of a straight line y=mx+c I would advise practicing it without using a calculator

Answer 2

using a calculator: You can do this using "statplots".

First, enter the data using the "Stat" button and then edit. Put the x values in L1 and the y-values in L2 (make sure they're in the same order--i.e. X1 matches up with Y1, and X2 matches up with Y2)

Now go to 2nd "Y=", which is statplot.Turn statplot1 on, and make sure that the x-list is L1, and the y-list is L2. If you enter zoom 9, this will scale the window for your data, and show the two points.

But you also want to plot the line, which you can do as a linear regression. Back to the stat button: hit stat, and go right one to the "calc" menu. Option 4 is a linear regression: enter 2nd 1 (L1), 2nd 2 (L2), vars - y-vars-- function--Y1 (enter)
This will perform the linear regression between the two points, give you the equation, and plot the line (as Y1). If you go back to graph, you'll see it...

And two points had better define a straight line! This technique will get you ready for doing lines of best fit through data which does NOT all lie on one line... (or other types of regression which are not straight line...)