How to draw a linear equation line using two points

[TacoMix]

Hi, I had a Further Maths Sac today about bivariate data. I skipped one question because I didn't know how to answer it. I couldn't remember the question properly but it was about this: they gave me a set of data (20) and asked me to draw a scatter plot for it,, then asked me to calculate the least square regression. Then they asked me something about using the two points and connects the line together ( those points must fit the equation in one decimal place). I'm just wondering how would you do that. Do you just sub x = 0 to the equation or using three median line ? ( they didn't ask for it though)

Thank you very much

[Yacoubb]

Hi, I had a Further Maths Sac today about bivariate data. I skipped one question because I didn't know how to answer it. I couldn't remember the question properly but it was about this: they gave me a set of data (20) and asked me to draw a scatter plot for it,, then asked me to calculate the least square regression. Then they asked me something about using the two points and connects the line together ( those points must fit the equation in one decimal place). I'm just wondering how would you do that. Do you just sub x = 0 to the equation or using three median line ? ( they didn't ask for it though)

Thank you very much

This process is called superimposition. So you basically choose two x values (I choose 0 and the largest), and you substitute it into the least squares regression line, and find the y value for the corresponding x.

For example, the equation of the least squares regression line is y = x + 3

I choose x = 0 and x =10

y = 0 + 3 = 3
y = 10 + 3 = 13

So now, I have two points (0,3) and (10,13). You place those two points onto your cartesian plain and then join them up. You then extend it and make the least squares regression line long enough to look prominent, and label it as the least squares regression line, and of couse the equation (in my example, y = x + 3).

[TacoMix]

Thank you very much Yacoubb. I have one more question which concerns me. draw in the 'break' symbol to indicate that there's numbers inbetween 0 to 300, but when I substitute x=0, I get -6.48. Where is the right place to put this ? Do I have to make another break symbol ( or the lightning/thunder/flash symbol) ?

Thank you once again and sorry for my bad English

[Yacoubb]

Thank you very much Yacoubb. I have one more question which concerns me. draw in the 'break' symbol to indicate that there's numbers inbetween 0 to 300, but when I substitute x=0, I get -6.48. Where is the right place to put this ? Do I have to make another break symbol ( or the lightning/thunder/flash symbol) ?

Thank you once again and sorry for my bad English

Hey thats alright okay so well maybe if thats happening you may want to choose a point that will give you a positive value. So maybe substitute x = 100 for example, or any other x value that gives you a positive value. It is much easier to obviously graph it when its positive

Hope that helped!