x/(y+z)+y/(z+x)+z/(x+y)=1 chứng minh rằng x*x/(y+z)+y*y/(z+x)+z*z/(x+y)= 0 hộ mk với

$\begin{array}{l}\underline{\text{Đáp án:}}\\x.\dfrac{x}{y+z}+y.\dfrac{y}{z+x}+z.\dfrac{z}{x+y}=0\\\underline{\text{Giải thích các bước giải:}}\\x.\dfrac{x}{y+z}+y.\dfrac{y}{z+x}+z.\dfrac{z}{x+y}\\=x.(\dfrac{x}{y+z}+1-1)+y.(\dfrac{y}{z+x}+1-1)+z.(\dfrac{z}{x+y}+1-1)\\=x.\dfrac{x+y+z}{y+z}-x+y.\dfrac{x+y+z}{z+x}-y+z.\dfrac{x+y+z}{x+y}-z\\=(x+y+z)(\dfrac{x}{y+z}+\dfrac{y}{z+x}+\dfrac{z}{x+y})-(x+y+z)\\=x+y+z-(x+y+z)\\=0(ĐPCM)\\\underline{\text{CHÚC BẠN HỌC TỐT}}\\\end{array}$