Mathematics: Post your doubts here!

[Dhaval Shah]

how we solve tan^2???can usolve it
http://olevel.sourceforge.net/papers/9709/9709_s12_qp_11.pdf

Its simple! Ok, the equation that you form will be (tan^2x/3) < 1, then you take 3 to the other side making it tan^2x < 3, then you square root both sides making it tanx < (square root) 3. Then using precise angles (not exactly sure what its called) you should know that tan inverse (square root) 3 is 60 degrees, or (pie)/3. You get it? So x < ((pie)/3)

 

[hussamh10]

can sme1 help me with the cosine curves in as.like i have problms in this equation 3-4cosx.

 

[hussamh10]

Its simple! Ok, the equation that you form will be (tan^2x/3) < 1, then you take 3 to the other side making it tan^2x < 3, then you square root both sides making it tanx < (square root) 3. Then using precise angles (not exactly sure what its called) you should know that tan inverse (square root) 3 is 60 degrees, or (pie)/3. You get it? So x < ((pie)/3)

yeah Thanx man i get ...

 

[Farru]

i hv a ques,
its ques no 2 , nov 2011, var 11.
pls ppl tel me, tht how cn we find out tht the gradient is neg. :/
i hv seen da mark scheme but its really brief.
rep asap!

 

[leadingguy]

i hv a ques,
its ques no 2 , nov 2011, var 11.
pls ppl tel me, tht how cn we find out tht the gradient is neg. :/
i hv seen da mark scheme but its really brief.
rep asap!

can u please post the link??

 

[Farru]

Thank you very much!

thr he have taken y=1, whreas in ur ques it was y=1/2
thrfre just telng u , tht acc to the ques, u wll gt 4 roots... not 3.

 

[Farru]

can u please post the link??

http://www.xtremepapers.com/papers/...S Level/Mathematics (9709)/9709_w11_qp_11.pdf

ques. 2

 

[leadingguy]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_11.pdf

ques. 2

just find the dy/dx of the eq. it will be as follows:
9x^2 -12x + 4 = dy/dx
now use completing square .

it will be like

3(3x -2 )^2 -4 + 4 = y this resembles the eq. of curve i.e y = mx + C


here m = (3x - 2)^2 having squre on it proves that it can never be negative I am not sure that I have explained good enough but it is somehow this way.

 

[elbeyon]

I remember doing this question, and getting it wrong lol. Convergent means like the GP is going to a number but it never actually gets to that number, like you know when r of the GP is less than 1 and you have to find the sum to infinity, thats the number that it approaches but it will never get to that number! So basically you will say ((Second Term of GP)/(First Term of GP)) < 1 . Then you solve that equation that you get...

Now I'm clear. Thanks a ton buddy !

 

[aloha]

p3?

yep

 

[Taiyaba]

Your working is right, but the Number of terms between 7 & 13 should be 7, not 6. If you use that the sum = 203 which i think is correct


Are you sure, i doubt it. Like even if you do it without using a formula (getting all the terms up to 13 and then adding from the 7th to the 13th) you won't get that answer :/

Yes it is and I hv solved it also

 

[Dhaval Shah]

Yes it is and I hv solved it also

Alright, how did you solve it?

 

[Taiyaba]

Alright, how did you solve it?

d=-3-(-7)=4
7th term = a+(7-1)d=
=-7+(6*4)
=17
30th term=a+(30-1)d
=-7+(29)(4)
=109

Now a=17 and l=109

n=30-6=24
Sn=n/2(a+l)
Sn=24/2(17+109)
Sn=1512

 

[elbeyon]

Can any one explain to me how to get set of values as k < -√(48) and k > √(48) while solving k > +- √(48) type question. When are we supposed to use the < sign and when > sign ?

 

[Tkp]

View attachment 16207

ok but the timeperiod is 360 so it completes one rotation at 360

 

[shanky631]

whitecorp plz help me in this question.

 

[parthrocks]

ok but the timeperiod is 360 so it completes one rotation at 360

 

[NokiaN95638]

can anyone differentiate ths xy(x+y) plzz???

Ok man, u hav 2 use the UV method 4r this and differentiate in terms of x.
xy(x+y)= (x^2).y+x(y^2) ( now differentiate this using UV method)

d((x^2).y+x(y^2))= x^2.1(dy/dx)+y.2x+ x.2y(dy/dx)+ y^2.1

therefore ur answer is:

x^2(dy/dx)+2xy+2xy(dy/dx)+y^2.

Hope it is the correct answer. Check it up.

Cheers mate

 

[Dhaval Shah]

d=-3-(-7)=4
7th term = a+(7-1)d=
=-7+(6*4)
=17
30th term=a+(30-1)d
=-7+(29)(4)
=109

Now a=17 and l=109

n=30-6=24
Sn=n/2(a+l)
Sn=24/2(17+109)
Sn=1512

Ohhh, my bad!! I thought you said 13th instead of 30th, i guess i read it wrong in your original post Yeah, you are right!

 

[Yousif Mukkhtar]

Can someone explain q7 iii)
http://www.xtremepapers.com/papers/...S Level/Mathematics (9709)/9709_w10_qp_12.pdf