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
Candice
Candice

secondary 4 chevron_right A Maths chevron_right Singapore

Good afternoon! How do i do qns 35? Just part i will do :)

Date Posted: 1 week ago
Views: 3
Eric Nicholas K
Eric Nicholas K
1 week ago
Hi Candice! We show that dy/dx < 0 for all x.

Another way is to do long division and reasoning.

y = (16 - 3x) / (x + 3)

dy/dx
= (x + 3) (-3) - (16 - 3x) (1), whole thing divided by (x + 3)^2

= -9 divided by (x + 3)^2

(x + 3)^2 is always non negative but here it cannot equal zero since it is in denominator

So dy/dx < 0 for all x except 3

*correction to previous line: except -3*
Eric Nicholas K
Eric Nicholas K
1 week ago
I will pen this down at a later time when I am free and if no one has written them yet
Candice
Candice
1 week ago
It is ok! I understand it now :D Thank u for the quick response!

See 1 Answer

done {{ upvoteCount }} Upvotes
clear {{ downvoteCount * -1 }} Downvotes
Arnold K H Tan
Arnold K H Tan's answer
866 answers (A Helpful Person)
Alternate method:
For a decreasing function, show dy/dx is always negative for all relevant values of x.
Candice
Candice
1 week ago
Ok thank u! :)