高数极限lim[1-cosx(cos2x)^(1/2)]/x^2求解,快
问题描述：
高数极限lim[1-cosx(cos2x)^(1/2)]/x^2求解,快
答
lim1-cosx(cos2x)^(1/2)/x^2=lim1-cosx(cos2x)^(1/2)*1+cosx(cos2x)^(1/2)/{x^21+cosx(cos2x)^(1/2)}=lim1-cosx^2cos2x/{x^21+cosx(cos2x)^(1/2)}=lim1-cosx^2(cosx^2-sinx^2)/{x^21+cosx(cos2x)^(1/2)}=limcosx^2+s...