设2个交点为(x1,y1),(x2,y2)则有y1-y2=x1-x2+m-m=x1-x2,且(x+m)²/9+x²/16=1即25/144·x²+2m/9·x+m²/9-1=0,所以|x1-x2|=√(4m²/81-4X25/144X（m²/9-1）)/（25/144）=24√（25-m²...