to ask for help with some maths homework?

[ChunkysMum]

Differentiate the following wrt x1 and x2:

f=-(1-t^2)/(x1+x2t)

Hmmm.

Actually, I think it's simpler if I call x1, A and x2, B. So:

Differentiate the following wrt A and B:

f = -(1-t^2)/(A+Bt)

Are B and A both variables?

Is t a constant or a variable?

OK - is this further maths? Partial differentialtion? is t a variable?

Jeez, it was 1+1 in my day so I'm running after Spotty and Lee !

Sorry cant help; this is why Ive started sending dd age 4 to kumon, so she's not a thicko in maths like me.

trinity- ah fond memories!! Also, legless!!

it looks like t is the variable, then it's a case of using the quotient rule

f' = vu'-uv'/v2 where v = (A+Bt) and u = -(1-t2)

Is this a proof/ generalisation thingy? Can you give the esact question? Have you timesed out the brackets?

8008135 and 1391355

so v' (dv/dt) = B and u' (du/dt) = 2t

Oh threads getting serious now, time to leave!

Second the quotient rule I've read the question properly lol Its not as hard as it looks

then f' = ((A+Bt)2t+(1-t2)B)/(A+Bt)2

if A and B are variables then it's a cse of partial differentiation which I can come back to if you want

Feeling a bit thick - what's 1391355?

what does (x1+x2t) mean? x+2Xt or x+2t?

The way I've answered is differentailting wrt t (and giving answer in terms of A and B) which isn't what you've written

Thank you Ninja, it's been a while since I've done this sort of maths (years) and a friend has asked.

I've passed on your posts.

Oh dear Ninja, I've messaged to ask if the wording is the exact question.

I agree with ninja if it's a simple variable in t

Oh I saw it as Using the pruduct rule within the quotient rule? I am no good with maths on a computer or in any way I don't write it >

and then partialy differentiating...? I think my brain just dribbled out my ear

Just clarified, what is in the OP is the exact question. Can you differentiate wrt A and B?

Sorry, if that doesn't make sense.