lim(x,y)→(0,0)(1-cos(x2+y2))/(x2+y2)x2
问题描述:
lim(x,y)→(0,0)(1-cos(x2+y2))/(x2+y2)x2
lim(x,y)→(0,0)(1-cos(x2+y2))/(x2+y2)x2y2
答
=lim(x,y)→(0,0) (1/2)·(x2+y2)²/(x2+y2)x2y2
=lim(x,y)→(0,0) (1/2)·(x2+y2)/x2y2
→∞