## 1018 one year ago find df/dx and df/dy :

1. 1018

$\sqrt{4x ^{2} + 3y ^{2}}$

2. welshfella

first simplify this a bit = [ (4x^2 + 3y^2)^½]^3 = (4x^2 + 3y^2)^(3/2)

3. welshfella

now you use the chain rule

4. welshfella

oh!! or is this partial differentiation??

5. 1018

wait, sorry, the derivatives are to be solved separately. like dx first then dy haha sorry

6. 1018

cause i saw that you should treat y as a constant etc etc for dx and vice versa for dy...

7. welshfella

yes - oh - its been a long time i'm struggling to remember this stuff...

8. 1018

haha, im just studying it right now and already struggling. lol. so, am i right?

9. welshfella

yes - you have the general idea but i'm a bit hazy on it to be honest

10. 1018

im just wondering if y is to be constant, so finding dx would just be sqrt(4x^2) dx ?

11. 1018

the radical is confusing me i might get it wrong

12. welshfella

i'm sure some of the other guys will be more familiar with it than i am.

13. welshfella

well chage the radical to an exponent as i have done

14. 1018

1/2 right?

15. 1018

ok i think i got it from here. haha. thanks!

16. welshfella

square root = ^(½) yes

17. welshfella

yw