log3^7=a,log7^4=b,用a,b表示log14^84

ngqs2022-10-04 11:39:541条回答

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hj_hj0126 共回答了15个问题 | 采纳率86.7%
log3^7=a,log7^4=b,得log7^2=b/2
log14^84=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)+2b/(2+b)+2/(2a+ab)
1年前

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