• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Mathematics: Post your doubts here!

Messages
44
Reaction score
32
Points
18
For who ever is having trouble viewing my pictures, please PM me you email address and I'll send you the images, other than that GOOD LUCK FOR ALL OF US TOMORROW!!
 
Messages
29
Reaction score
3
Points
3
When the tangent is parallel to the y axis, the dy/dx is infinity. To express infinity= 1/0
So we equate the dy/dx=1/0
y/[x(3y^3-1)] = 1/0
cross multiplying:
x(3y^3-1)=o

3y^3-1=0
y= cube root of (1/3)
y= 0.693

Substitue this value into x(3y^3-1)=o to find the x coordinate.

how did u do i) part? I did but I didn't get the answer
 

Jaf

Messages
321
Reaction score
232
Points
53
When the tangent is parallel to the y axis, the dy/dx is infinity. To express infinity= 1/0
So we equate the dy/dx=1/0
y/[x(3y^3-1)] = 1/0
cross multiplying:
x(3y^3-1)=o

3y^3-1=0
y= cube root of (1/3)
y= 0.693

Substitue this value into x(3y^3-1)=o to find the x coordinate.
The issue I had with the answer to this is that instead of rounding off to 0.693 before substitution into the equation, I continue to use cuberoot of 1/3, and end up getting a different answer for the x coordinate (the difference is quite a bit actually). Confusing. :S
 

Jaf

Messages
321
Reaction score
232
Points
53
Dude, just multiply your two answers from part i) to get one quadratic factor and find the other one by (Ax^2 + Bx + C) inspection.
That is, the roots you get in i) are 1 - √2 i and 1 + √2 i. So the factors become (x-1+√2 i)(x-1-√2 i). You multiply the brackets and you'll see everything in terms of 'i' gets cancelled to give you a quadratic factor of x^2 - 2x +3.

If you still don't get it, let me know I'll post a screenshot.
 
Messages
118
Reaction score
165
Points
53
Never really understood what they did. I would want some help in this question as well!

November 2012 P3, was the hardest paper which CIE released since 2002 ! :eek:
Lets hope we get one which will be much easier tomorrow so that we all can ace Insha Allah :)
 
Top