log3^7=a,log7^4=b,用a,b表示log14^84
问题描述：
log3^7=a,log7^4=b,用a,b表示log14^84
答
log3^7=a,log7^4=b,得log7^2=b/2log14^84=log14^7+log14^12=1/(log7^14)+2log14^2+log14^3=1/(log7^7+log7^2)+2/log2^14+1/log3^14=1/(1+b/2)+2/(log2^7+1)+1/(log3^7+log3^2)=2/(2+b)+2/(2/b+1)+1/(a+ab/2)=2/(2+b)...