exam questions..

[kdgamz]

Im a bit confused with VCAA exam 1..clarification would be appreciated...

question 1. a)
the answer is =  but i wrote

am i allowed to do this?

if so then part b) becomes -1/9, whereas the answer says 1/9 because it used = 

are both acceptable??


thanks

[TonyHem]

2xy-9y^2 + 9 = 0.
and when y = 1,
2x(1)-9(1)+9 = 0
x = 0
So -1/(0-9(1)) = 1/9

[kamil9876]

if so then part b) becomes -1/9, whereas the answer says 1/9 because it used

I don't even know the question but I can tell from here that what you are saying is not true. Notice that:



Since you can get one from the other by multiplying by . What this means is that for any and . The two expressions must be the same, hence if some x and y give 1/9 for one expression, they must give 1/9 for the other.

[kdgamz]

if so then part b) becomes -1/9, whereas the answer says 1/9 because it used

I don't even know the question but I can tell from here that what you are saying is not true. Notice that:



Since you can get one from the other by multiplying by . What this means is that for any and . The two expressions must be the same, hence if some x and y give 1/9 for one expression, they must give 1/9 for the other.

thats the thing it becomes -1/9  for the expression i used, and 1/9 for the expression in the answer..

this is 2006 VCAA exam 1

EDIT: sorry i just realised :laugh: