Differentiation Help

Where do I even start? And someone show me the steps to do this please? Thanks in advance Screenshot 2020-11-30 203105.png

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Reply 1

davros

Original post by Tee.Q

Where do I even start? And someone show me the steps to do this please? Thanks in advance Screenshot 2020-11-30 203105.png

Surely you can make a start? They have given you a function I so the first step is to differentiate it (and then a second time) :smile:

Reply 2

Tee.Q

Original post by davros

Surely you can make a start? They have given you a function I so the first step is to differentiate it (and then a second time) :smile:

Someone sent me the solution but I just don't know how they got there.

Reply 3

davros

Original post by Tee.Q

Someone sent me the solution but I just don't know how they got there.

OK, but can you make a start on the differentiation? What do you get for dI/dt?

Reply 4

Tee.Q

Original post by davros

OK, but can you make a start on the differentiation? What do you get for dI/dt?

I'll try my best to get dI/dt :biggrin:

Reply 5

Tee.Q

Original post by davros

OK, but can you make a start on the differentiation? What do you get for dI/dt?

I feel like I'm doing something wrong :frown:

Reply 6

B_9710

Original post by Tee.Q

I feel like I'm doing something wrong :frown:

You need to use the product rule

Reply 7

davros

Original post by Tee.Q

I feel like I'm doing something wrong :frown:

Unfortunately you are!

You have a product of 2 functions so you need to use the product rule to differentiate - does this ring any bells? Also you've brought out a 't' factor when I would expect either an 'a' or a 'w' :smile:

Reply 8

Tee.Q

Original post by B_9710

You need to use the product rule

My bad. Thanks :smile:

Reply 9

Tee.Q

Original post by davros

ohhhh okay i will take out w when i differentiate it

Reply 10

Tee.Q

Original post by Tee.Q

ohhhh okay i will take out w when i differentiate it

Am I on the right track?

Reply 11

Tee.Q

ohhh you meant the a in -at to be taken out

Reply 12

B_9710

Original post by Tee.Q

Am I on the right track?

Look at that first term again. What do you go when you differentiate

e^{-at}

Reply 13

Tee.Q

Original post by B_9710

Look at that first term again. What do you go when you differentiate

e^{-at}

Do you get

-ae^{-at}

Reply 14

davros

Original post by Tee.Q

Do you get

-ae^{-at}

That's right :smile:

Are you out of practice on these ? :smile:

Reply 15

Tee.Q

Original post by davros

That's right :smile:

Are you out of practice on these ? :smile:

🤣🤣 I was fairly decent at these before quarantine but im forgetting a lot of stuff now. I will try getting the second derivative on my own but I don't know what it means when it says "show I(t) is a solution of of equation 1". And thank you guys for having patience with me. You're truly amazing :smile:

Reply 16

Tee.Q

Original post by davros

That's right :smile:

Are you out of practice on these ? :smile:

I've now done the second derivative. What does it mean when it says "show that I(t) is a solution of equation 1"?

Reply 17

davros

Original post by Tee.Q

I've now done the second derivative. What does it mean when it says "show that I(t) is a solution of equation 1"?

I haven't checked your derivatives. but it basically means that if you plug your expressions for d^2I/dt^2, dI/dt and I into the left hand side of equation (1) then you should find that things magically cancel out and you get 0 as the result :smile:

Reply 18

username5491034

is this A level maths ?