D
duylinh1811


1. tìm m để các hệ phương trình sau có nghiệm:
a) [tex]\left\{ \begin{array}{l} \sqrt[]{x}+\sqrt[]{y}=1 \\ x\sqrt[]{x}+y\sqrt[]{y}=1-3m \end{array} \right.[/tex]
b) [tex]\left\{ \begin{array}{l} \sqrt[]{x+1}+\sqrt[]{y+2}=m \\ x+y=3m \end{array} \right.[/tex]
c) [tex]\left\{ \begin{array}{l} x+y+x^2+y^2=8 \\ xy(x+1)(y+1)=m \end{array} \right.[/tex]
a) [tex]\left\{ \begin{array}{l} \sqrt[]{x}+\sqrt[]{y}=1 \\ x\sqrt[]{x}+y\sqrt[]{y}=1-3m \end{array} \right.[/tex]
b) [tex]\left\{ \begin{array}{l} \sqrt[]{x+1}+\sqrt[]{y+2}=m \\ x+y=3m \end{array} \right.[/tex]
c) [tex]\left\{ \begin{array}{l} x+y+x^2+y^2=8 \\ xy(x+1)(y+1)=m \end{array} \right.[/tex]