Question

Find the derivative of the function below.
http://www.webassign.net/cgi-perl/symimage.cgi?expr=h%28y%29%20%3D%20%28b%2F%28a%2By%5E4%29%29%5E3

Answer 1

you need to use the chain rule

Answer 2

so it would be 3(b/a+y^4)^2 * the derivative of b/(a+y^4)

Answer 3

i keep getting 3(a/a+y^4)^2 * ((a+y^4)-b(4y^3))/(a+y^4)^2 But it says its wrong

Answer 4

ok I think you might be missing a step. I got (a+y^4 -1 -4y^3)/ (a+y^4)
assuming that your class uses all letters as variables... My calc book uses "lower letters" ie a, b, c.... as constants, and "higher letters" ie x, y, z as variables

Answer 5

dont you have to use quotient rule though?

Answer 6

sorry i think its actually (a+y^4) [(b(a+y^4) - b(1+4y^3)] / (a+y^4)

Answer 7

yes you do, you can then also simply since you have (a+y^4) on the top and bottom so
(a+y^4) [(b(a+y^4) - b(1+4y^3)] / (a+y^4)^2
becomes
[(b(a+y^4) - b(1+4y^3)] / (a+y^4)

Answer 8

Yah, no quotient rule :D assuming those letters are constants.
Just write the (a+y^4) with a -1 power

Answer 9

Hmm this might be an easier way to do it :O
Just distributing that cube to the top and bottom. Hmm