y= (t^3 + t)/(t^4 - 2)

y'=

This is derivative of a division (fraction.

the rule is

the denominator times the derivative of the numerator - the numerator times the derivative of the denominator.

ALL OVER the denominator squared.

The denominator of the derivative is the easy part. It is just (t^4 -2)^2

Now.. lets work on the other part.

(t^4 -2)(3t^2+1)-(t^3+t)(4t^3)

You have to multiply and simplify the numerator and put it over the denominator. Be careful of the negative signs.