voi a,b,c,d, la cac so duong thoa man a*b = c*d =1 chung minh bat dang thuc : ( a+b )*( c+d ) +4 >= 2*( a+b+c+d ) cac ban oi giup minh voi OK

voi a,b,c,d la cac so duong thoa man a*b = c*d = 1. Chung minh bat dang thuc ( a+b )*( c+d ) + 4 >= 2( a+b+c+d ) 

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 , d thoa man ab=cd. Chung minh:

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

cho a,b,c la cac so duong thoa man (1/a+1/b+1/c)>=(a+b+c), chung minh a+b+c>=3abc

cho a,b,c la cac so duong thoa man (1/a+1/b+1/c)>=(a+b+c), chung minh a+b+c>=3abc

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

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

Cho a, b, c, d la cac so nguyen duong  thoa man a²+b²=b²+d². CM a+b+c+d la hop so

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