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Mathematics: Post your doubts here!

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Can anyone please give me notes or explain the topic of Range and Domains! i still have no idea about it :( :(
 
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Guys, can somebody please help me? This is the third time I'm asking this.

Qs.1) Find the values of k such that the straight line y=2x+k meets the curve with equation x^2+2xy+y^2=5 exactly once.

Qs.2) An Open cylindrical wastepaper bin, of radius r cm and capacity Vcm^3 is to have a surface area of 5000 cm^3.
(a) Show that V=1/2r(5000πr^2)
(b) Calculate the maximum possible capacity of the bin.

Qs.3) Find the equation of the normal to the curve y=8/1-x^3 at the point (-1,4)
 
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I Have the only thing remaining is functions and as 2 days are left i cant get it from any book thats y i asked u :(
 

Dug

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Guys, can somebody please help me? This is the third time I'm asking this.

Qs.1) Find the values of k such that the straight line y=2x+k meets the curve with equation x^2+2xy+y^2=5 exactly once.

Qs.2) An Open cylindrical wastepaper bin, of radius r cm and capacity Vcm^3 is to have a surface area of 5000 cm^3.
(a) Show that V=1/2r(5000πr^2)
(b) Calculate the maximum possible capacity of the bin.

Qs.3) Find the equation of the normal to the curve y=8/1-x^3 at the point (-1,4)

In Q2, isn't it V=1/2r (5000-pi r^2)
 

Dug

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I Have the only thing remaining is functions and as 2 days are left i cant get it from any book thats y i asked u :(
Ok lets see...Try asking one question at a time. I mean divide your problems as that would make it easier for me to answer and for you to understand.
 
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For Q2:
S.A=2πrh + πr^2
2πrh + πr^2 = 5000
h = (5000-πr^2)/2πr

V=πr^2h
V=πr^2 [(5000-πr^2)/2πr]
V=2500r - πr^3 / 2
V=(1/2)(r)(5000-πr^2)
CAN U TELL ME IN OLEVEL LOCI THERE IS QUESTION BISECT LINE ABC?
 
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@roadtrip9o9
Core maths has some really good explanations for functions and graphs. min and max is also eplained well in that book.i suggest you get that. You'l waste time here. and wont get the whole picture.
 

Dug

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Guys, can somebody please help me? This is the third time I'm asking this.

Qs.1) Find the values of k such that the straight line y=2x+k meets the curve with equation x^2+2xy+y^2=5 exactly once.

Qs.2) An Open cylindrical wastepaper bin, of radius r cm and capacity Vcm^3 is to have a surface area of 5000 cm^3.
(a) Show that V=1/2r(5000πr^2)
(b) Calculate the maximum possible capacity of the bin.

Qs.3) Find the equation of the normal to the curve y=8/1-x^3 at the point (-1,4)
For Q2 part b
Set dV/dr = 0
You get r = 530.5
Find an expression for second derivative and insert this value of r.If you get a maxima with this value, put this value in the v=1/2r(5000-πr^2). I don't know if its correct. Whats the answer for this question?
 

Dug

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@roadtrip9o9
Core maths has some really good explanations for functions and graphs. min and max is also eplained well in that book.i suggest you get that. You'l waste time here. and wont get the whole picture.
Are you implying that i am wasting his time? :p
 
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For Q2 part b
Set dV/dr = 0
You get r = 530.5
Find an expression for second derivative and insert this value of r.If you get a maxima with this value, put this value in the v=1/2r(5000-πr^2). I don't know if its correct. Whats the answer for this question?
The answer is 38500 cm^3.
 

Dug

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Guys, can somebody please help me? This is the third time I'm asking this.

Qs.1) Find the values of k such that the straight line y=2x+k meets the curve with equation x^2+2xy+y^2=5 exactly once.

Qs.2) An Open cylindrical wastepaper bin, of radius r cm and capacity Vcm^3 is to have a surface area of 5000 cm^3.
(a) Show that V=1/2r(5000πr^2)
(b) Calculate the maximum possible capacity of the bin.

Qs.3) Find the equation of the normal to the curve y=8/1-x^3 at the point (-1,4)
For Q3)
dy/dx = 8(1-x^3)^(-1-1) (-1) (-3x^2)
dy/dx = 24x^2/(1-x^3)^2
Inserting x = -1
dy/dx = 24(-1)^2 / (1-(-1)^3)^2
dy/dx = 24/4
dy/dx = 6

Eq of the normal :-
Gradient of the normal = -1/6
4=-1(-1/6) + c
c = 23/6
y = -1/6x + 23/6

Again, the accuracy of my answers is not guaranteed. :whistle:
 
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