Answer:
a) The sequence converges to 0
b) The lenght of the curve is 
Step-by-step explanation:
Consider the sequence 
a) We will prove it using the sandwich lemma. Note that for all n
, then

Note that the expressions on the left and the right hand side have a greater degree on the denominator than the one on the numerator. Then, by takint the limit n goes to infinty on both sides, we have that

So, the sequence converges to 0.
b) The function
the formula of curve lenght is given by
![s = \int_a^b \sqrt[]{1+(f'(x))^2}dx](https://tex.z-dn.net/?f=s%20%3D%20%5Cint_a%5Eb%20%5Csqrt%5B%5D%7B1%2B%28f%27%28x%29%29%5E2%7Ddx)
in this case, a=1, b=6
Note that
. Then
. Take u = 1+36x. Then du= 36dx (i.e du/36 = dx). If x = 1, then u = 37 and if x = 6 then u = 217. So,