已知f(x)=x平方减x加k,log小2f(a)=2,f(log小2a)=k,且a不等于1求a,k的值急

显示全部楼层 · 2010-10-8 22:40:00

log2f(a)=2f(a)=a2-a+k=4k=-a2+a+4f(log2(a))=[log2(a)]2-log2(a)+k=klog2(a)[log2(a)-1]=0log2(a)=0,log2(a)=1a≠1，所以log2(a)=1a=2k=-a2+a+4=2

千问 · 2010-10-8 22:40:00

f(x)=x^2-x+kf(log(2)a)=[log(2)a]2-log(2)a+k=klog(2)a[log(2)a-1]=0log(2)a=0,log(2)a=1a≠1，所以a=2log(2)f(a)=2f(a)=a2-a+k=2^2=4k=4-a2+a=4-4+2=2即a=2,k=2

千问 · 2010-10-8 22:40:00

a(n+1)-1/3=4an-1-1*3=4an-4/3a(n+1)-1/3=4(an-1/3)[a(n+1)-1/3]/(an-1/3)=4所以an-1/3是等比数列[a(n+1)-1/3]/(an-1/3)=4所以q=4a1-1/3=5/3所以an=(5/3)*4^(n-1)

已知f(x)=x平方减x加k,log小2f(a)=2,f(log小2a)=k,且a不等于1求a,k的值 急