Mathematics: Post your doubts here!

[ahmed abdulla]

MECHANICS ....
can any one give my the idea of how to do this question ... i dont have nothing to do !
http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_w07_qp_4.pdf
q7 (ii) and (iii) ????????

 

[syed1995]

I tried that, I'm pretty sure I'm using b^2-4ac wrong.
This is the equation I'm getting when they're equated: y^2+2k-4y-13 = 0 ..

What's A , B and C... 4 terms. I forgot how to do these x_x

You need to take the equation in terms of X.

 

[ZainH]

You need to take the equation in terms of X.

All right, in that case I get : x²+8x+k²-52 = 0

 

[MustafaMotani]

MECHANICS ....
can any one give my the idea of how to do this question ... i dont have nothing to do !
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w07_qp_4.pdf
q7 (ii) and (iii) ????????

bro if p moves up then it means tension has to be greater than all the opposing forces

hope it helps.. as for part iii i dont have m1 so i dont know wahts coeffiecient of friction..

 

[Maz]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w12_qp_12.pdf
3(ii) Please!
Thnx.

 

[xhizors]

I tried that, I'm pretty sure I'm using b^2-4ac wrong.
This is the equation I'm getting when they're equated: y^2+2k-4y-13 = 0 ..

What's A , B and C... 4 terms. I forgot how to do these x_x

in b2-4ac put these values from ur eq
(2k-4)^2-4(1)(-13)

 

[MustafaMotani]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_12.pdf
3(ii) Please!
Thnx.

its easy if you have done part (i)

its just like finding minimum value of the function..

first find dA/dx and then equate it to zero ... whatever value u get for x ... substitute that value in original function to get the minimum area..

 

[GorgeousEyes]

please nov 07 no 3 ii

 

[syed1995]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_12.pdf
3(ii) Please!
Thnx.

dA/dx = 0 .. find x.

Equate x into the A equation..

 

[Rutzaba]

I dint guys i asked

 

[ZainH]

in b2-4ac put these values from ur eq
(2k-4)^2-4(1)(-13)

That doesn't work :|
K doesn't come as 8.5.

 

[syed1995]

please nov 07 no 3 ii

from part i .. 32 + 80u + 80u^2

u = x+x^2 ..

expand the above equations with these data.. and find the coefficent of x^2 by adding all the x^2 variables..

 

[GorgeousEyes]

from part i .. 32 + 80u + 80u^2

u = x+x^2 ..

expand the above equations with these data.. and find the coefficent of x^2 by adding all the x^2 variables..

could u do the steps if u have time ?

 

[syed1995]

From your initial equation
(1)y^2-(4)y+(2k-13) = 0

a=1
b=4
c=2k-13

b^2-4ac=0
16-4(1)(2k-13)=0
16-8k+52=0
8k=68
k=8.5

 

[syed1995]

That doesn't work :|
K doesn't come as 8.5.

that above was for you ^^

 

[Maz]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_12.pdf
4(i)
I'm not at my best today.
herein, i got themethod from the ms but not why.

 

[ZainH]

From your initial equation
(1)y^2-(4)y+(2k-13) = 0

a=1
b=4
c=2k-13

b^2-4ac=0
16-4(1)(2k-13)=0
16-8k+52=0
8k=68
k=8.5

So I didn't need it in terms of x
Now I get it, you switched the equation so the value for C wouldn't have a 'y' in it.
Thanks for the , how many times has it been now? 3rd? Haha

 

[syed1995]

32 + 80u + 80u^2

u = x+x^2 ..

32+ 80(x+x^2) + 80(x+x^2)^2
32+80x+80x^2 + 80(x^2+2x^3+x^4)
32+80x+80x^2+80x^2+160x^3+80x^4
160x^2
160 coeffiecent.

 

[sma786]

daredevil , MustafaMotani thanks boys

 

[Maz]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_12.pdf
4(i)
I'm not at my best today.
herein, i got themethod from the ms but not why.

anyone???