IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => IGCSE/ GCSE => Math => Topic started by: 7ooD on May 17, 2009, 05:03:33 pm

Title: paper 4 help plzz just two questions
Post by: 7ooD on May 17, 2009, 05:03:33 pm

in paper 4 june 2007 q )4 c it asks k is an integer for which the equation f(x)=k has exactly 2 solutions use the graphs to find the 2 values of k i kno the answer but i just want explanation y those points we choosen  second question is 7 )d) same paper i got the area but is there is a formula which uses perimeter * length to give the surface area cuz in ms they used it 

Title: Re: paper 4 help plzz just two questions
Post by: angell on May 17, 2009, 05:04:46 pm

n  i need help in june 2000...q.2 d)iii

im gettin the wrong answer:S how do we get 99/100 for that one????

Title: Re: paper 4 help plzz just two questions
Post by: Ghost Of Highbury on May 17, 2009, 05:10:18 pm

@7ood
for the 4c u have to imagine a line parallel to x - axis which when extended on both sides will cut the graph at two points...
if u see clearly at (-9,0) and (3,0) a line will cut the graph at 2 points..
so the answers is....-9,3

Title: Re: paper 4 help plzz just two questions
Post by: Ghost Of Highbury on May 17, 2009, 05:17:21 pm

@angell..
okk...so the probability of not needing more than three attempts to pass is

1- (probability of needing more than three attempts to pass)

the probability of needing more than three attempts to pass is if he fails in the first three attempts
the probability of failing in the first attempt is 1/4
second attempt is (1-4/5) = 1/5
and third too is 1/5 (because they say any future attempts)

therefore u multiply them = 1/4 * 1/5 * 1/5 = 1/100

1 - 1/100 = 99/100
answer - 99/100
good luck

Title: Re: paper 4 help plzz just two questions
Post by: angell on May 17, 2009, 05:23:33 pm

thnkx..best ov luck 2u 2:D:D n i totallly got it:P:D

Title: Re: paper 4 help plzz just two questions
Post by: Ghost Of Highbury on May 17, 2009, 05:24:50 pm

thanks...but i don't have my exams...i'm appearing for the november 2009 exams..

Title: Re: paper 4 help plzz just two questions
Post by: 7ooD on May 17, 2009, 06:04:22 pm

thanks but for the love of god somebody answer my second q and if there is another answer for the first one cuz i dnt get it

Title: Re: paper 4 help plzz just two questions
Post by: Ghost Of Highbury on May 17, 2009, 06:18:12 pm

i'm sry i cud not explaint it to u..

but i have tried showing it in the graph too....plz find the image attached ...

hope it helps u
and the second question..
i don't think there is any formula that links perimeter to the length...

Title: Re: paper 4 help plzz just two questions
Post by: 7ooD on May 17, 2009, 06:50:05 pm

thanks so much i understood it  ;D just last part to make sure we choose the coordinates of (0,3) and (9,6) cuz the others points are not integers and k should be integer right ?

Title: Re: paper 4 help plzz just two questions
Post by: Ghost Of Highbury on May 17, 2009, 07:09:48 pm

u don't choose the co-ordinates ...u name the 2 lines...

the first line is y=3
and second one is y=-9

we choose only these 2 lines because only these lines intersect the graph at 2 distinct point or lemme say have 2 sollutions...

happy to help you