B1. Cho f(1)=1008,f(1)+f(2)+...+f(n)=n^2.f(n) f(n)la ham so duong
tinh f(2015)
B2 Cho cac so nguyen to q,p,r,s sao cho cac so sau deu la so nguyen to p^s+s^q,q^s+s^r,r^s+s^p
tim cac so p,q,r,s
B3 co a,b,c duong a mu 3+bmu3=c^3
so sanh a^2015+b^2015 va c^2015
cho a,b,c,d la cac so nguyen duong doi 1 khac nhau thoa man a/a+b + b/b+c + c/c+d + d/d+a =2
CMR abcd la 1 so chinh phuong
cho 4 so nguyen duong a b c dsao cho a2 + b2 = c2+d2 .CMR: tong a+b+c+d la hop so
Cho a,b,c la cac so nguyen duong thoa man: abc=1. CMR
\(\frac{1}{a^3\left(b+c\right)}+\frac{1}{b^3\left(c+a\right)}+\frac{1}{c^3\left(a+b\right)}\ge\frac{3}{2}\)
cho cac so nguyen duong a,b,c thoa man :(a,b,c)=1;ab=c(a+b).Cm a+b la so chinh phuong
co cac so nguyen duong a,b.c nguyen to cung nhau tm (a+b)=ab cmr a+b la co chinh phuong
Cho cac so nguyen duong a b c thoa man
(a+1)^3+(b+2)^3+(c+3)^3=3(a+1)(b+2)(c+3)
cho cac so nguyen duong a,b,c thỏa man ab+a+b=3 tìm GTNN của a2+b2
cho 3 so nguyen duong a,b,c co tong bang 1 cmr P=1/a+1/b+1/c>=9