Question

以5为底3的对数是几？

Answer 1

log5(3)=ln3/ln5

手算的话就用级数

ln(1+x)=x-x^2/2+x^3/3-x^4/4+...+(-1)^n*x^(n+1)/(n+1)+...(-1<x<=1)

当x超出这个范围可以转化一下

例如ln3=ln(3/2)+ln2

=ln(1+1/2)+ln(1+1)

扩展资料

对数的运算法则：

1、log(a) (M·N）=log(a) M+log(a) N

2、log(a) (M÷N)=log(a) M-log(a) N

3、log(a) M^n=nlog(a) M

4、log(a)b*log(b)a=1

5、log(a) b=log (c) b÷log (c) a

Answer 2

log5 3＝lg3÷lg5＝0.4771÷0.6990＝0.6825.