已知f1(x)=e^xsinx,fn(x)= fn-1'(x),n≥2,求f1(0)+f2(0)+f3(0)+ ……f2011(0)的值

来源:学生作业帮助网 编辑:六六作业网 时间:2024/11/17 07:26:34
已知f1(x)=e^xsinx,fn(x)=fn-1''(x),n≥2,求f1(0)+f2(0)+f3(0)+……f2011(0)的值已知f1(x)=e^xsinx,fn(x)=fn-1''(x),n≥2

已知f1(x)=e^xsinx,fn(x)= fn-1'(x),n≥2,求f1(0)+f2(0)+f3(0)+ ……f2011(0)的值
已知f1(x)=e^xsinx,fn(x)= fn-1'(x),n≥2,求f1(0)+f2(0)+f3(0)+ ……f2011(0)的值

已知f1(x)=e^xsinx,fn(x)= fn-1'(x),n≥2,求f1(0)+f2(0)+f3(0)+ ……f2011(0)的值
f1(x)=e^xsinx f1(0)=0
f2(x)=f1'(x)=(e^xsinx)'=e^x(sinx+cosx) f2(0)=1
f3(x)=[e^x(sinx+cosx)]'=2e^xcosx f3(0)=2
f4(x)=(2e^xcosx)'=2e^x(cosx-sinx) f4(0)=2
f5(x)=-4e^xsinx f5(0)=0
f6(x)=f5'(x)=(-4e^xsinx)'=-4e^x(sinx+cosx),f6(0)=-4f2(0)
.
每四项和,成等比数列,且公比为-4
前四项的和为5,再下面为-20,80,.
2011/4=502.3,第502项为-20*(-4)^(501),
第503项为5*(-4)^(502),但最后只有3项和为5*(-4)^(502)*3/5=3*(-4)^(502),
f1(0)+f2(0)+f3(0)+ ……f2011(0)=5(1-(-4)^(502))/(1-(-4))+3*(-4)^(502),
=4^502-1+3*4^502=4^503-1.

f1 ' (x) = e^x (sinx + cosx) = √2 e^x (sin(x+π/4)
f2(x) = √2 e^x (sin(x+π/4)
fn(x) = (√2)^(n-1) e^x sin【x+(n-1)π/4 】
f1(0)+f2(0)+f3(0)+ ……f2011(0)
= 【0 + √2 sin (π/4) + 2 sin(π/2) + ...

全部展开

f1 ' (x) = e^x (sinx + cosx) = √2 e^x (sin(x+π/4)
f2(x) = √2 e^x (sin(x+π/4)
fn(x) = (√2)^(n-1) e^x sin【x+(n-1)π/4 】
f1(0)+f2(0)+f3(0)+ ……f2011(0)
= 【0 + √2 sin (π/4) + 2 sin(π/2) + (√2)^3 sin (3π/4) + 0
+ (√2)^5 sin (5π/4) +(√2)^6 sin (6π/4) + (√2)^7 sin (7π/4) 】
+ 【(√2)^8 sin (2π) + ...... 】+ 0 + (√2)^2009 sin (2009π/4) + (√2)^2010 sin (2010π/4)
= (-15) [ 1 + 16 + 16^2 + ......+ 16^250 ] + 2^1004 + 2^1005
= ( 1 - 16^251) + 2^1004 + 2^1005
=2^1005+1

收起

已知f1(x)=e^xsinx,fn(x)= fn-1'(x),n≥2,求f1(0)+f2(0)+f3(0)+ ……f2011(0)的值 已知f1(x)=e^xsinx,fn(x)= fn-1'(x),n≥2,求f1(0)+f2(0)+f3(0)+ ……f2011(0)的值 已知f(x)=x/(x 1),f1(x)=f(x),fn(x)=fn-1[fn-1(x)]求f100(x)的值 已知f1(x)=(2x-1)/(x+1),fn+1(x)=f1[fn(x)](n=1,2,3,……),求f30(x) 已知F1(x)=2/(1+x),定义Fn+1(x)=F1[Fn(x)],an=[Fn(0)-1]/[Fn(0)+2],则数列an的通项公式是 已知f(x)=e^xsinx,求y求y 已知函数f1(x)=(2x-1)/(x+1) 对于n∈N* 定义fn+1(x)=f1( fn(x)) 求fn(x)解析式苏教版高中数学选修2-2p78页最后一题 f1(x)=2/(x+1),而fn+1=f1[fn(x)],设an=[fn(2)-1]/[fn(2)+2],则a99= 已知函数f(x)=x/(1+|x|),设f1(x)=f(x),fn+1(x)=f[fn(x)],求f2(x),并求fn(x)通项公式 已知f1(x)=(2x-1)/(x+1),对于n=1,2,…,定义fn+1(x)=f1(fn(x)),若f35(x)=f5(x),则f28(x)=? f(x)=x/(1+x) x>=0 f1(X)=f(X) fn(X)=fn-1[fn-1(x)]求fn(x)证明:f1(X)+2f2(X)+3f3(x)+……+nfn(X) f1(x)=2/(1+x),f(x)=f1[fn(x)],an=[fn(0)-1]/[fn(0)+2],则a2010=? 设f1(x)=2/(1+x),定义f(n+1)(x)=f1[fn(x)],an=[fn(0)-1]/[fn(0)+2],则a(2007)等于 已知f(x)=x+1/2 x属于[0,1/2],2(1-x)定义fn(x)=f(fn-1(x))已知f(x)=x+1/2 x属于[0,1/2],2(1-x),x属于【1/2,1],定义fn(x)=f(fn-1(x)),其中f1(x)=f(x),则f2011(1/5)= 已知f1(x)=sinx+cosx,fn+1(x)是fn(x)的导函数,f2(x)=f1‘(x),f(x)=f2’(x).fn+1(x)=fn‘(x),n∈N+,则f2011(x)= 已知F1=1/(1-1/x),……Fn+1=1/(1-Fn) n为正整数,请用x的代数式表示F2003 设 f(x)=sinx,f1(x)=f'(X),f2(X)=f1'(X).fn+1(X)=fn'(X) n属于N+ 求f2007(X)=? 已知n为正整数,规定f1(x)=f(x),fn+1(x)=f(fn(x)),且f(x)=2(1-x),0《x《1;f(x)=x-1,1