Qualification > Math
Additional Math Help HERE ONLY...!
jellybeans:
--- Quote from: A@di on June 05, 2010, 06:21:09 am ---oh damn..........this is such a bloody hard q......i remember givin this to ma teacher and he couldnt solve it..........
there are two different cases you need to consider......the first is that he selects 3 sweets all of different kinds......u knw that he can choose any 3 flavours frm the 6 available.....the number of selections is 6C3=20
the second case is that 2 of the sweets are the same and the other one is of a different flavour. when he chooses the first sweet, he has a choice between 6 different flavours. when he chooses the second sweet he still has a choice between 6 flavours since he can select another of that
flavour. but when he selects the third sweet he has a choice of 5 flavours since two sweets have already been taken form the sixth flavour and he
cannot take a third. the number of selections is 6*5=30
so the total is 30+20=50
--- End quote ---
:o :o :o :o OMG LOL i asked my teacher as well and i think he explained it 4 times but i still had NO IDEA what he was talking about. :P i did get it for a second but then i forgot D:
ANYWAYS;
'the second case is that 2 of the sweets are the same and the other one is of a different flavour. when he chooses the first sweet, he has a choice between 6 different flavours. when he chooses the second sweet he still has a choice between 6 flavours since he can select another of that
flavour. but when he selects the third sweet he has a choice of 5 flavours since two sweets have already been taken form the sixth flavour and he
cannot take a third. the number of selections is 6*5=30'
ummm i get the first part but for the second case, why is it not 6*6*5 if he has a chance of choosing 6 diff flavours the first time, 6 the next, & 5 on his third choice? :-[
thankyouuuus.
Ghost Of Highbury:
Told ya, its a crappy q..!! i might have to look at the ms...can u post the ms link plz? ?
jellybeans:
--- Quote from: A@di on June 05, 2010, 06:41:50 am ---Told ya, its a crappy q..!! i might have to look at the ms...can u post the ms link plz? ?
--- End quote ---
haha :P
Ghost Of Highbury:
The "Two of one kind" means can choose from 6 flavours .... the "+1" means , only 5 flavours as one of the flavour doesn't exist anymore..
s 6*5...
Dibss:
5 A function f is defined by for the domain x 0.
(i) Evaluate f^2(0). [3]
(ii) Obtain an expression for f^-1. [2]
(iii) State the domain and the range of f^-1. [2]
I don't understand how to get the correct answer for part (iii) so could someone please help me?
Mark scheme attached.
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