Mathematics: Post your doubts here!

[Yash Kothari]

Need urgent help in inequalities !
0580/42/M/J/12 Question no. 3 a to b and c (2)
Thank in advance

See....
a)
he needs minimum 4 lemon trees and as u know lemon trees are x so...
x>=4
then he he needs minimum 9 orange trees and as u know orange trees are y so...
y>=9
and together lemon trees and orange trees shudnt exceed 20 so...
x+y<=20

b)
5X + 10Y <=170
dividing all by 5,
we get
x+ 2y<=34

see...thats simple

 

[Mahmood Magdy]

See....
a)
he needs minimum 4 lemon trees and as u know lemon trees are x so...
x>=4
then he he needs minimum 9 orange trees and as u know orange trees are y so...
y>=9
and together lemon trees and orange trees shudnt exceed 20 so...
x+y<=20

b)
5X + 10Y <=170
dividing all by 5,
we get
x+ 2y<=34

see...thats simple

thank you
But what about part c ??

 

[Fayax555]

thank you
But what about part c ??

use x=4, y=9, x+y=20 and x+2y=34 to draw the lines of the graph.

 

[Mahmood Magdy]

use x=4, y=9, x+y=20 and x+2y=34 to draw the lines of the graph.

and the final answer also !! What is it ?? Thanks a lot by the way

 

[Fayax555]

When you have finished shading all the unwanted regions, shape in the red line will be remaining and that is the wanted region.
3 c (ii) from the wanted region find x+y=20.
that will be x is 11, y is 9 ( it is the yellow dot). 11+9=20.
in part b, cost is mentioned. lemon trees(x) cost $5 each and orange trees( y ) costs $10 each. that is 5x+10y
since the x is 11 and y is 9, lets replace them by numbers.
so the final answer is 5 x 11 + 10 x 9 = 145.

 

[Imaan]

Hey I know I sound like a baby LOL :$ , but can someone please help explain me how to work the gradient of a tangent? I am doing one from this paper, question 2 and (c). I drew my line at x = -4 but can't come right with the gradient.
If you want I can take a photo of it, instead of the person having to plot all the points again.

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Mathematics (0580)/0580_w12_qp_41.pdf

The answer sheet says from 6 to 11.

Thanks

 

[Fayax555]

Hey I know I sound like a baby LOL :$ , but can someone please help explain me how to work the gradient of a tangent? I am doing one from this paper, question 2 and (c). I drew my line at x = -4 but can't come right with the gradient.
If you want I can take a photo of it, instead of the person having to plot all the points again.

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Mathematics (0580)/0580_w12_qp_41.pdf

The answer sheet says from 6 to 11.

Thanks

take a photo then.

 

[Imaan]

Here is it. Just don't laugh at it !

 

[laamya pk]

i have a question about the accuracy of the answer .Even though the answers are said to be given in 3 s.f in some of the answers this is not applied.so,i would like to know what exactly shud we follow???

 

[Kdown567]

In

i have a question about the accuracy of the answer .Even though the answers are said to be given in 3 s.f in some of the answers this is not applied.so,i would like to know what exactly shud we follow???

In theory it should be that you use 3 s.f. For all questions except where cambridge specifically tells you not to or in some things where it says give this as an exact figure / write all numbers shown in calculator

If you look at some of the mark schemes you can see that they award the mark for a range (which includes with and without 3 s.f.

 

[Fayax555]

Here is it. Just don't laugh at it !

Your line(tangent) didn't even touch the graph. Your tangent should be little closer to the curve..
Try to touch that line(tangent) in the red dot (x=-4) and it shouldn't touch no where else.

 

[Imaan]

Your line(tangent) didn't even touch the graph. Your tangent should be little closer to the curve..
Try to touch that line(tangent) in the red dot (x=-4) and it shouldn't touch no where else.

Ok, but still the point is how to work out the gradient of the tangent.

 

[Fayax555]

Ok, but still the point is how to work out the gradient of the tangent.

Just take two coodinates of x and y. (x1,y1) (x2,y2)
Gradient=(difference in y-coordinates) divided by (difference in x-coordinates)
Since tangent is a straight line, you can find its gradient.

 

[joanna omar]

Any notes with all the sequence tricks ?

 

[snailey]

Can someone help me with the questions in paper 4 generally where they ask the the speed at which water flows when it flows from a cylindrical tube to a container?
There is similar question in May/June 2013 paper 42 sum 9.

 

[Imaan]

Just take two coodinates of x and y. (x1,y1) (x2,y2)
Gradient=(difference in y-coordinates) divided by (difference in x-coordinates)
Since tangent is a straight line, you can find its gradient.

Thanks a million. I really appreciate your answer and help. God bless...

 

[Fayax555]

Thanks a million. I really appreciate your answer and help. God bless...

You're welcome.

 

[***amd***]

Can someone help me with the questions in paper 4 generally where they ask the the speed at which water flows when it flows from a cylindrical tube to a container?
There is similar question in May/June 2013 paper 42 sum 9.

link plz

 

[Fayax555]

link plz

Oh no, let me answer that question.

 

[***amd***]

Oh no, let me answer that question.

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