M
muluoitrai


1. tim so n co 3 c/s abc thoa man: abc=c^5+ a x b
2. tim 3c/s tan cung cua so a^(9^(9^9))
3. tinh tong
f=1!x3+2!x7+3!x13+...+k!x(k^2+k+1)+...+12!x(12^2+12+1)
4. tim so du cua phep chia: M=x^(3n) + x^n + 1 cho (x^2 + x+1)