求lim x->∞ （xtan2/x+(1/x^2)*（sin）x^2）等於多少

上式=lim x->0((tan2x/)x)+lim x->∞ ((sinx^2)/x^2)
=lim x->0(sin2x/(x*cos2x))+lim t->∞(sint/t) (令t=x^2)
=lim x->0(sin2x/x)+1
=2+1=3