展开全部
解：(a) f(x)=d[sin(9x^2)/(9x^2)/dx=[18xcos(9x^2)9x^2-sin(9x^2)18x]/(81x^4)
=[162x^3cos(9x^2)-18xsin(9x^2)]/(81x^4)
=2cos(9x^2)/x-2sin(9x^2)/(9x^3).
(b)
f''(√π)={[-2*18xsin(9x^2)x-2cos(9x^2)]/x^2-[2*18xcos(9x^2)9x^3-2*27x^2sin(9x^2)]/(81x^6)}(√π)
=[-36sin(9x^2)-2cos(9x^2)/x^2-4cos(9x^2)/x^2+2sin(9x^2)/(3x^4)](π)
=-6cos(9π)/π=6/π
=[162x^3cos(9x^2)-18xsin(9x^2)]/(81x^4)
=2cos(9x^2)/x-2sin(9x^2)/(9x^3).
(b)
f''(√π)={[-2*18xsin(9x^2)x-2cos(9x^2)]/x^2-[2*18xcos(9x^2)9x^3-2*27x^2sin(9x^2)]/(81x^6)}(√π)
=[-36sin(9x^2)-2cos(9x^2)/x^2-4cos(9x^2)/x^2+2sin(9x^2)/(3x^4)](π)
=-6cos(9π)/π=6/π
已赞过
已踩过<
评论
收起
你对这个回答的评价是？
推荐律师服务：
若未解决您的问题，请您详细描述您的问题，通过百度律临进行免费专业咨询
