Question

lim(x趋向于正无穷)2xsin2/x 的极限

Answer 1

lim(x->∞) 2x sin(2/x)
=lim(x->∞) 4 sin(2/x)/(2/x)
=4 lim(x->∞) sin(2/x)/(2/x) //:y=2/x x->∞,y->0
=4 lim(y->0) siny/y
=4 × 1
=4