1)Prove that if n is an odd positive integer, then

N = 2269n + 1779n + 1730n ¡ 1776n

is an integer multiple of 2001... 2)Factor the expression

30(a2 + b2 + c2 + d2) + 68ab ¡ 75ac ¡ 156ad ¡ 61bc ¡ 100bd + 87cd: 3) Prove that for every x∈R is true this equation: x^8+x^6-x^3-x+1>0,,, 4) Make the add:1^2+2^2-3^2+… +〖( n-1)〗^2+n^2 which n∈ N ,,,,5) Find the last digit of 777^777