对于函数f(x)=lg1+x/1-x,若f(y+z/1+yz)=1,f(y-z/1-yz)=2,其中-1<y<

学习 时间:2026-04-03 09:41:43 阅读:372
对于函数f(x)=lg1+x/1-x,若f(y+z/1+yz)=1,f(y-z/1-yz)=2,其中-1<y<1,-1<z<1,求f(yf(Y)和f(z)的值

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光亮的白云

友好的巨人

2026-04-03 09:41:43

注意到:Ka=1+(y+z)/(1+yz)=(1+y+z+yz)/(1+yz)=(1+y)(1+z)/(1+yz)Kb=1-(y+z)/(1+yz)=(1-y-z+yz)/(1+yz)=(1-y)(1-z)/(1+yz)Kc=1+(y-z)/(1-yz)=(1+y-z-yz)/(1-yz)=(1+y)(1-z)/(1-yz)Kd=1-(y-z)/(1-yz)=(1-y+z-yz)/(1-yz)=(1-y)(1+z)/(1-yz)所以:Ka/Kb=[(1+y)/(1-y)][(1+z)/(1-z)]Kc/Kd=[(1+y)/(1-y)][(1-z)/(1+z)]因为f(x)=lg[(1+x)/(1-x)]所以f((y+z)/(1+yz))=lg(Ka/Kb)=lg[(1+y)/(1-y)][(1+z)/(1-z)]=lg[(1+y)/(1-y)]+lg[(1+z)/(1-z)]=f(y)+f(z)同理f((y-z)/(1-yz))=f(y)-f(z)解方程组:f(y)+f(z)=1f(y)-f(z)=2可得:f(y)=1。5f(y)=-0。5

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  • 动人的雪碧
    回复
    2026-04-03 09:41:43

    注意到:Ka=1+(y+z)/(1+yz)=(1+y+z+yz)/(1+yz)=(1+y)(1+z)/(1+yz)Kb=1-(y+z)/(1+yz)=(1-y-z+yz)/(1+yz)=(1-y)(1-z)/(1+yz)Kc=1+(y-z)/(1-yz)=(1+y-z-yz)/(1-yz)=(1+y)(1-z)/(1-yz)Kd=1-(y-z)/(1-yz)=(1-y+z-yz)/(1-yz)=(1-y)(1+z)/(1-yz)所以:Ka/Kb=[(1+y)/(1-y)][(1+z)/(1-z)]Kc/Kd=[(1+y)/(1-y)][(1-z)/(1+z)]因为f(x)=lg[(1+x)/(1-x)]所以f((y+z)/(1+yz))=lg(Ka/Kb)=lg[(1+y)/(1-y)][(1+z)/(1-z)]=lg[(1+y)/(1-y)]+lg[(1+z)/(1-z)]=f(y)+f(z)同理f((y-z)/(1-yz))=f(y)-f(z)解方程组:f(y)+f(z)=1f(y)-f(z)=2可得:f(y)=1。5f(y)=-0。5

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