Question

How do i differentiate this?

Answer 1

\[y = 2r^{2} + \frac{200}{r}\]

Answer 2

@saifoo.khan

Answer 3

use chain rule on the first term

Answer 4

i mean power rule

Answer 5

can u show the working?

Answer 6

\[\Large y = 2r^2 +200r^{-1}\]

Answer 7

@thushananth01 , how was your yesterday's exam? :D

Answer 8

yeah it was easy...but lost 3 marks :P...

Answer 9

3 marks is ok.

Answer 10

hm yes, lets see, how paper 2 goes...

Answer 11

derivative of 2r^2 = \((2\times 2)r^{2-1}\)

Answer 12

then the derivative of the other one?

Answer 13

the derivative of 200r^(-1) = \((200 \times -1)r^{-1 - 1}\)

Answer 14

\[-200^{-2}\]

Answer 15

yup that

Answer 16

oh wait no

Answer 17

it's \(-200r^{-2}\) dont forget r

Answer 18

oh sorry, i know :P

Answer 19

rewrite as \(-\frac{200}{r^2}\) for beauty purposes

Answer 20

i used differentiation to find the tangent at the point (2.25, 100) how should i do it? to find the gradient of the tangent?

Answer 21

i know not the gradient you speak about...i hate math terms lol

Answer 22

hmmm @saifoo.khan might knw?

Answer 23

@Hero

Answer 24

Now, insert 2.25 instead of x.

dy/dx is basically the rate of change of something

Answer 25

oh..that's the gradient? lol

Answer 26

LOL, ofc.

Answer 27

yes i get it....:) @saifoo.khan i

Answer 28

It's very easy and the best math i like. ;)

Answer 29

i dint still learn this, but its interesting!

Answer 30

it's very easy and very very interesting.
i can teach you if you are stuck anywhere. ;)

i had Add-maths too in O-levels.

Answer 31

wow, how much did u score for that?

Answer 32

B.

Answer 33

:'(

Answer 34

thats good, u did O level last year?

Answer 35

Yes. im currently in AS.

Answer 36

Great

Answer 37

It's very fun and intresting. my last exam is on 14th.
if you need any help regarding anything you can always knock me. :)

Answer 38

definitely BRO:)

Answer 39

@saifoo.khan , when gradient =0 how do i find r?
0 = 4r - 200r^-2

Answer 40

when gradient = 0, it means that dy/dx is equal to 0.

Answer 41

yes

Answer 42

now when dy/dx = 0, solve the equation out.

Answer 43

how to solve?

Answer 44

factor out your r and then solve for r\[r(4-200r)=0\]

Answer 45

\[r=0\] or
\[4-200r=0\]

Answer 46

the exponential is -2...o.O

Answer 47

@hero, can u help..