old ruse question (2 Viewers)

[altSwift]

Did they make a mistake on line two, with x(x-a)?? [When I multiplied out, i got x(x+a), ending up with the locus as a circle with centre (-a/2, b/2) instead of (a/2, b/2)]

also, is there supposed to be a restriction on the locus? like excluding (a,0) (because z =/ a on the denominator)

Thanks!

 

[fan96]

Note the denominator in the first line



That looks wrong. However they later multiplied by instead, so it seems two mistakes have cancelled out?

I don't think there are any further restrictions.

The only conditions given to you are



and

 

[darkk_blu]

in the very first line, its works out as

 

[altSwift]

Note the denominator in the first line



That looks wrong. However they later multiplied by instead, so it seems two mistakes have cancelled out?

I don't think there are any further restrictions.

The only conditions given to you are



and

ahh I see it now haha, yeah that confused me for a while.

so would they give a specific condition for z =/ a for some locus question like

 

[darkk_blu]

I can't believe that question was also in my 4U test today, but I really shouldn't have been. I stuffed up and put instead, lol, lost a mark.

 

[altSwift]

I can't believe that question was also in my 4U test today, but I really shouldn't have been. I stuffed up and put instead, lol, lost a mark.

rip, are you from ruse as well?

 

[fan96]

ahh I see it now haha, yeah that confused me for a while.

so would they give a specific condition for z =/ a for some locus question like

I'm not sure what you're asking, sorry.

 

[darkk_blu]

rip, are you from ruse as well?

Nah, I'm not that smart, btw do you know if people actually get 100 in ext 2 or is that just scaling?

 

[camelrider]

The graph of a locus represents all the possible points that satisfies a given equation.

You have to exclude (a,0), as it lies on the circle.

Otherwise, you are saying that z=a satisfies Re(z-ib/z-a)=0, which is false.

 

[altSwift]

Nah, I'm not that smart, btw do you know if people actually get 100 in ext 2 or is that just scaling?

100 as in raw mark? Apparently Anthony Henderson from USYD got 100% in 93'

 

[altSwift]

The graph of a locus represents all the possible points that satisfies a given equation.

You have to exclude (a,0), as it lies on the circle.

Otherwise, you are saying that z=a satisfies Re(z-ib/z-a)=0, which is false.

I was thinking this... I wonder why they didn't include it in the answers, thanks!

I'm not sure what you're asking, sorry.

All good, camel just explained it