cho cac so nguyen duong a,b,c , d thoa man ab=cd. Chung minh:

A=\(a^{2008}+b^{2008}+c^{2008}+d^{2008}\) la hop so

cho cac so nguyen duong a,b,c,d thoa man ab=cd. chung minh A=aⁿ + bⁿ + cⁿ + dⁿ la mot hop so voi moi so tu nhien n

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

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 x,y,z la cac so nguyen duong va x+y+z la so le, cac so thuc a,b,c thoa man (a-b)/x=(b-c)/y=(a-c)/z. chung minh rang a=b=c

Cho cac so duong abcd a+b+c+d =4.cm1/ab+1/cd+1/bc+1/da lon hon hoac bang a2+b2+c2+d2

Cho a, b, c, d la cac so nguyen duong thoa man a + b=c + d= 25

Tim GTLN cua M = \(\frac{c}{b}\)+ \(\frac{d}{a}\)

1. Cho a,b,c,d la cac so nguyen thoa man \(a^2=b^2+c^2+d^2\)

chung minh rang a.b.c.d + 2015 viet duoc duoi dang hieu cua 2 so chinh phuong.

2. Cho a,b la cac so duong thoa man dieu kien a+b=1. tim gia tri nho nhat cua bieu thuc

\(P=\frac{2+a}{\sqrt{2-a}}+\frac{2+b}{\sqrt{2-b}}\)

B1: cho a,b,c la cac so nguyen duong

CMR:neu a /b >hoac bang c/d thi a/b > hoac bang a+c/b+d > hoac bang c/d

B2: Tim PS nho nhat khac 0 sao cho khi chia no cho 14/9 ; cho 45/27 deu duoc thuong la cac so tu nhien 

B3:CMR: 1/2^2 + 1/4^2 + 1/6^2 +....+ 1/100^2 < 1/2