Ask Singapore Homework?

Upload a photo of a Singapore homework and someone will email you the solution for free.



Question

secondary 4 | A Maths
One Answer Below

Anyone can contribute an answer, even non-tutors.

Answer This Question
girl
Girl

secondary 4 chevron_right A Maths chevron_right Singapore

I’m not sure how to do part (ii). I’ve not checked if my (i) is correct

Date Posted: 4 years ago
Views: 217

See 1 Answer

done {{ upvoteCount }} Upvotes
clear {{ downvoteCount * -1 }} Downvotes
Eric Nicholas K
Eric Nicholas K's answer
5997 answers (Tutor Details)
1st
Girl, the difficulty here lies in understand the meaning of “minimum gradient” when usually questions ask for “minimum point”. Let me know if you need more explanation.
girl
Girl
4 years ago
I got it ! Im just not accustomed to doing d3y/dx3 in questions like this, snd usually stop at d2y/dx2. Ive never done a question like this before so thanks for helping out :D
Eric Nicholas K
Eric Nicholas K
4 years ago
Girl, can think of the gradient equation of the curve (dy/dx = ...) as a separate variable z, where z = dy/dx.

z = x^2 - 16/x^2

From here, we find the minimum value of z, which is dz/dx = 0.

The second derivative test here is d2z/dx2, which corresponds to the original d3y/dx3.
girl
Girl
4 years ago
I’ll think about that . Thank you ☺️
girl
Girl
4 years ago
Thank you :)