∵直线y=x+m与 椭圆 x^2/144 + y^2/25 = 1 有两个公共点∴将y=x+m代入x^2/144 + y^2/25 = 1有两解 x^2/144 +(x+m)²/25=1 则 25x²+144(x+m)²=3600 即 169x²+288mx+144m²-3600=0 Δ=(288m)²-4×169×(144m²-3600) =-14400m²+2433600>0解得 -13