9Log以3为底5的对数等于多少的解法
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log2(25)*log3(1/16)*log5(1/9)=[2log2(5)]*[-4log3(2)]*[-2log5(3)=[2*lg5/lg2]*[-4*lg2/lg3]*[-2*lg3/lg5
[log9(4)+log3(8)]/log1/3(16)=[lg4/lg9+lg8/lg3]/[lg16/lg1/3]=[2lg2/2lg3+3lg2/lg3]/[4lg2/(-lg3)]=4lg2/
因为log以3为底2的对数=1/log以2为底3的对数同理可得,log以3为底5的对数=1/log以5为底3的对数所以n=log以3为底2的对数+log以3为底5的对数所以n=log以3为底10的对数
log以2为底25的对数乘以以3为底4的对数乘以5为底9的对数=lg25/lg2*lg4/lg3*lg9/lg5=2lg5/lg2*2lg2/lg3*2lg3/lg5=4lg5/lg3*2lg3/lg
lg2=mlg3=n故lg6=m+nlg5=lg10-lg2=1-mlog以5为底6的对数=lg6/lg5=(m+n)/(1-m)
log3(x/3)=log3(x)-log3(3)=log3(x)-1以上是根据对数的运算法则;
9乘以log以3为底5的对数=9×[(log5)÷(log3)]=9×[0.69897000433601880478626110527551÷0.477121254719662437295027903
log2(25)*log3(4)*log5(9)=lg25/lg2*lg4/lg3*lg9/lg5(换底公式)=lg5^2/lg2*lg2^2/lg3*lg3^2/lg5=2lg5/lg2*2lg2/
8再问:是不是换成分数形式可以互相约掉再答:log2(25)*log3(4)*log5(9)=lg25*lg4*lg9/lg2*lg3*lg4=log2(4)*log3(9)*log5(25)=2*2
log2(25)*log3(4)*log5(9)=lg25/lg2*lg4/lg3*lg9/lg5(换底公式)=lg5^2/lg2*lg2^2/lg3*lg3^2/lg5=2lg5/lg2*2lg2/
log3^1=0
(lg3/lg5)[(3lg5)/(3lg3)]=1
log以根号3为底2的对数中的根号3等于3的1/2次方,则log以根号3为底2的对数等于1/2的倒数倍的2log以3为底2的对数,其结果就等于2log以3为底2的对数.
2.321928,可以直接用计算机计算,或者用excel函数计算.
log8(9)*log9(8)=(log9/log8)*(log8/log9)=1
解题思路:本题柱考察学生对于对数的运算的理解和应用。解题过程:
2log3(2)-log3(32/9)+log3(8)-5*2*log5(3)=log3(4)-log3(32/9)+log3(8)-5*2*log5(3)=log3(4/(32/9))+log3(8
log9(27)=log3^2(3^3)=3/2log3(3)
利用:log(a^n)[b^m]=(m/n)log(a)[b]则:log(3)[2]=log(3²)[2²]=log(9)[4]