x＋2y＋2xy＝1则x=(1-y)/(1+2y)所以：m=2x+y=2(1-y)/(1+2y)+y=(2-2y+y+2y²)/(1+2y）=（2y²-y+2)/(1+2y)则2y²-(2m+1)y-(m+2)=0所以：（2m+1)²+8(m+2)≥0可求出m的范围.