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Đặt \(A=x+y+z\)
Theo BĐT cô si, ta có:
\(\left(x+y+z\right)\left(\frac{1}{x}+\frac{1}{y}+\frac{1}{z}\right)\ge3\sqrt[3]{xyz}.3\sqrt[3]{\frac{1}{xyz}}=9\)
Mà \(\frac{1}{x}+\frac{1}{y}+\frac{1}{z}=\frac{7}{10}\Rightarrow x+y+z\ge9-\frac{7}{10}=\frac{83}{10}\)
Vậy \(A_{min}=\frac{83}{10}\). Dấu "=" xảy ra \(\Leftrightarrow x=y=z=\frac{83}{30}\)
bai 1:Tim x,y,z \(\varepsilon\)Z ,sao cho :|x-y|+|y-z|+|z-x|+|z-t|+|t-x|=2003
bai 2:Cho bieu thuc:E=\(\frac{5-x}{x-2}\)tim gia tri nguyen cua x de
a) E co gia tri nguyen
b)E co gia tri nho nhat
cho x,y,z la cac so huu ti duong thoa man x+1/yz y +1/xz z+1/xy la cac so nguyen tim gia tri lon nhat cua bieu thuc A=x+y^2+z^3
tim gia tri nho nhat cua bieu thuc P = 14-x/4-x ; ( x thuoc z) khi do xnhan gia tri nguyen nao
Cho M :x-2/x+3
a, Tim x € Z de M co gia tri nguyen
b, Tim x € Z de M la gia tri nho nhat . Tim gia tri nho nhat do
Tim gia tri nho nhat cua P={x^2+1}^2+{y^4+5}^2
Tim gia tri nho nhat cua bieu thuc B = (x+1)^2+(y+3)^2+1
HELP ME !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Tim gia tri nho nhat cua bieu thuc
(x+1)^2+(y-2)^2+9
tim gia tri nho nhat cua bieu thuc M=(x-1)^2+(y+3)^2+5
cho bieu thuc M=(x-1)^2+(y+3)^2+2002. tim gia tri nho nhat cua bieu thuc m