/sci/ - Science & Math

[Anonymous No.1779620]

can someone explain how to do the composite rule in calculus for me,the text book is rally dense and ive just had someone shout at me for 3 hours for something i didnt do,not in the mood to read a long winded text when so many smart people are right on hand...

[fizixfag !2Vv6CKRC5w No.1779638]

Take for example the function
f(x)= (x^2+1)^3

You need to identify some inside function "u" in this case u=x^2+1

Thus we have f(x)=u^3

The derivative of this will be f'(x)=3u^2 * u'

From there you simply plug in "u" and solve

[fizixfag !2Vv6CKRC5w No.1779641]

>>1779638
Sorry if you wanted a more generalized idea, but I find the chain rule is best taught by example to many people.

[Anonymous No.1779676]

so say my function is

f(x)=sqrt(-5x^2+20x+8)

i need to factorise to get a closed function along the lines of (x+y)^2 (we will call this u)

then take the derivative of the origional function and multiply it by the closed function?

so k '(x) = f '(x) * u

[Anonymous No.1779681]

>>1779676
correction

and multiply it by the derivative of the closed function?

instead of

>and multiply it by the closed function?

[Anonymous No.1779692]

so k '(x) = f '(x) * 'u

[fizixfag !2Vv6CKRC5w No.1779697]

>>1779676
u=-5x^2+20x+8
f(x)=u^(-1/2)