1. ## Simple Differentiation help

i need to differentiate these 3 functions.
for a, am i supposed to use the quotient rule ? or would it just be 3x^2/1?
x by itself is equal to 1 right?
and constants are mostly ignored except for special situations?

Any help is appreciated, as i'm just learning how to do this and i don't have a textbook..

a) x^3+2 / x-5

3x^2(x-5) – 1 (x^3+2)/(x-5)^2

b) (2x^4 + x)(-4x^2 + 1)
c) Find dy/dx if y=2u^3 – 5u , u=x^3+2

2. Originally Posted by seanP
i need to differentiate these 3 functions.
for a, am i supposed to use the quotient rule ? or would it just be 3x^2/1?
x by itself is equal to 1 right?
and constants are mostly ignored except for special situations?

Any help is appreciated, as i'm just learning how to do this and i don't have a textbook..

a) x^3+2 / x-5

3x^2(x-5) – 1 (x^3+2)/(x-5)^2

b) (2x^4 + x)(-4x^2 + 1)
c) Find dy/dx if y=2u^3 – 5u , u=x^3+2
Yes, for the first one we have:

$y=\frac{x^3+2}{x-5}$

And use the quotient rule to get:

$\frac{dy}{dx} = \frac{(3x)(x-5)-(x^3+2)}{(x-5)^2}$

For the third one we have (by substituting the u in):

$y=2(x^3+2)^3-5(x^3+2)$

By using the chain rule on the exponents we get the following:

$\frac{dy}{dx} = (6)(x^3+2)^2(3x^2)-15x^2$

I figured you could figure out the second problem by these examples, but if you still want some help post here and I'll help some more

3. thanks for clearing that up