Mathematics: Post your doubts here!

[shingiechingz@8]

A spherical balloon is allowed to deflate. The rate at which the air is leaving the balloon is proportional to the volume, V of the air left in the balloon. When the radius of the balloon is 15cm, air is leaving at a rate of 8cm3/s find the expression of dV/dt.....please help

 

[Thought blocker]

A spherical balloon is allowed to deflate. The rate at which the air is leaving the balloon is proportional to the volume, V of the air left in the balloon. When the radius of the balloon is 15cm, air is leaving at a rate of 8cm3/s find the expression of dV/dt.....please help

dV/dt = -kV
V = (4/3)(pi)( r^3)
dV/dt = - k * (4/3)(pi)( r^3) ------ 1
when dV/dt = 8, r = 15 you can now find the value of k!
Then substitute that value in equation 1 to obtain the expression of dV/dt

dV/dt = - (2/1125pi)*V is the answer m getting.

 

[shingiechingz@8]

 

[shingiechingz@8]

#5

 

[Thought blocker]

integration of sec^2y.dy = integration of x.e^2x.dx (use integration by parts)

 

[Thought blocker]

#5View attachment 60955

(integrate using partial fractions) 1/N(1800 - N) .dN = 1/3600 . dt
integrate both sides.

for part (ii) substitute maximum value ur calc can take for t and see what ur coresponding N is

 

[Raja2396]

What is the easiest method to find term independent of x?

 

[shingiechingz@8]

What is the easiest method to find term independent of x?

I will show u by an example
find the indep of x in (x-2/x)^6
It would be 6Cr*x^(6-r)*(-2/x)^r
the term of x would be x^(6-r)*x^(-r)
The equate the powers of x to zero
6-r-r=0
therefore r=3
then substitute r
6C3*x^2*(-2/x)^2 would be the answer

 

[The Godfather]

MATH STUDENTS : https://www.xtremepapers.com/community/threads/skype-a-level-math-tuition-paper-1-2-3-7.44001/ PLEASE I NEED HELP AND I GURANTE IF U DO AS I SAY, YOU GONNA GET A*

 

[Thought blocker]

Notes on vectors ??

 

[Tahseen Islam]

Hey guys... This is my first post here.. Please help.. I am not able to do the part 4iii in the question paper in the link below... It is paper 5 mechanics... Thanks in advance... http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w11_qp_51.pdf

 

[Thought blocker]

Hey guys... This is my first post here.. Please help.. I am not able to do the part 4iii in the question paper in the link below... It is paper 5 mechanics... Thanks in advance... http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_51.pdf

Hardly anyone will have opt for paper 5 in thiscommunity.
u can post it here : https://www.facebook.com/groups/furthermathsprodigies/

 

[XPFMember]

Notes on vectors ??

Not sure if this will help https://www.xtremepapers.com/community/threads/my-summarized-vector-notes.15200/

 

[Thought blocker]

Not sure if this will help https://www.xtremepapers.com/community/threads/my-summarized-vector-notes.15200/

ty

 

[rilene]

may i ask a question?? If I retake my AS examination which mark will be considered in the end,the best or the most recent??

 

[Thought blocker]

may i ask a question?? If I retake my AS examination which mark will be considered in the end,the best or the most recent??

if u give math alone, n crosses u get low marks, then u can not show that to uni

 

[Tahseen Islam]

Hey guys... Can anyone please me with the math below... It is paper 3 vectors 10 ii... I can do part 10i... Please help...

 

[Thought blocker]

Hey guys... Can anyone please me with the math below... It is paper 3 vectors 10 ii... I can do part 10i... Please help...

Take myu as 0 and 1
So now u will have 3 points on plane
give them any letters for instance C and D
then do AC x AD and the cross product u get will be the normal vector of plane.
Then substitute values of and vector A,C or D in the equation of plane to get value of d in the equation : ax + by + cz = d where abc are points of normal and x y z are the point in which u have to substitue value of any vector on plane to get value of d.

 

[Thought blocker]

Hey guys... Can anyone please me with the math below... It is paper 3 vectors 10 ii... I can do part 10i... Please help...

After so long, i solved a math doubt on XPC xD
Bring it on... xD

well temme if m wrong in the above question

 

[Tahseen Islam]

After so long, i solved a math doubt on XPC xD
Bring it on... xD

well temme if m wrong in the above question

Absolutely right bro... Thanks a lot... Helped me a ton