For the first one, you can try to show that for . For the second one, the ratio test may be helpful.
Not completely off-topic question : If do English speaking people say that is an approximation of ? Is there another way of saying this ?
sorry, i found
the first one is less or equal to (n^3+8*n^2+1)/(n^4-n^2),
i think the later one is convergent. so the first one is convergent?
so how can u show that sequence tends to 1/n ????