lim(x趋向0)f(bx)/x =lim(x趋向0)f(bx)/(bx/a) *(b/2a)
而令t=bx/a,则lim(x趋向0)f(bx)/(bx/a)=lim(t趋向0)f(at)/t=1
所以lim(x趋向0)f(bx)/x =lim(x趋向0)f(bx)/(bx/a) *(b/2a)=1*(b/2a)=b/2a
lim(x趋向0)f(bx)/x =lim(x趋向0)f(bx)/(bx/a) *(b/2a)
而令t=bx/a,则lim(x趋向0)f(bx)/(bx/a)=lim(t趋向0)f(at)/t=1
所以lim(x趋向0)f(bx)/x =lim(x趋向0)f(bx)/(bx/a) *(b/2a)=1*(b/2a)=b/2a