靠,高数的题,limit x→0 [ f(ax)-f(-ax)]/x=lim x→0 [ f(ax)-f(0)+f(0)-f(-ax))]/x=lim x→0{ [ f(ax)-f(0)]/x+f(0)-f(-ax))]/x}=lim x→0{ [ f(ax)-f(0)]/x+lim x→0{ [ f(0)-f(-ax)]/x=af'(0)-(-af'(0))=2af'(0)
