be the ith
term of an Arithmetic Progression whose 1st
term is a and common difference d. Show that for any 2 positive integers m,n(>m), Σ(i:m to n)(Si
can't be a prime number.
Note: a,d are positive integers.
THE SUM OF CUBES ( Si)^3 of AP is always divisible by the sum of correspondng members of that AP - therefore it cannot be prime.
given 2,5,8,11,14 etc
2^3 +5^3 is divisible by 2+5
2^3 +5^3 + 8^3 is divisible by 2+5+8
2^3 +5^3 + 8^3+ 11^3+14^3 is divisible by 2+5+8+11+14
Now- go and prove it formally
Edited on March 7, 2008, 7:43 am