Im stuck on the following questions and need some help. Sorry I dont know how to do sigma and the writing to the right or up or below it so I list it in a clockwise motion from up to right to below.

Q1 - Calculate Sigma (20, (3+2r), r=1)

Q2 - The rth term of a series is u. Given that ur = u(r-1) +2 and u1 = 3. Write down u2, u3 and u4 hence find Sigma (n, Ur, r=1)

Q3 - The 8th term of an arithmetic series is 11 and the 15th term is 39 Find the common difference, the first term in the series and then the nth term.

Q4 - Find the sum of the intergers which are divisible by 3 and lies between 1 and 400, then find the sum of the intergers from 1 to 400 inclusive which arenotdivisible by 3.

Q5 - X(squared), (5x + 1) and (8x - 1) are the first three terms of an arithmetic series. Find the values of x and given that x>0 find the common difference and the first term.

Q6 - The sequnce u1, u2, u3 is generated from the relation

u(n+1) = n+1/n Un and U1 = 2 find the values of u2, u3 and u4

Sorry I asked for so much but I self teach and these are past paper questions that I don't understand, so sorry to cause trouble and if you dont mind can you also write out your workings as well to see how to come to that conclusion so I can handle questions of the smilar sort as future reference.

Thank You.