2(ax+by-ax)-(ax+by)^2-(by-ax)^2 其中a=-3 b=0.5
问题描述:
2(ax+by-ax)-(ax+by)^2-(by-ax)^2 其中a=-3 b=0.5
2(ax+by)(by-ax)-(ax+by)^2-(by-ax)^2
答
设ax+by=A;by-ax=B
2(ax+by)(by-ax)-(ax+by)^2-(by-ax)^2
=2AB-A^2-B^2
=-(A-B)^2
=-[(ax+by)-(by-ax)]^2
=-(2ax)^2
=-4a^2*x^2
=-36x^2