(1)已知lg3=0.4771, lgx=-3.5229,则x=? (2) 若log(3)2=a,用a表示代数式log(2)12=?

问题描述:

(1)已知lg3=0.4771, lgx=-3.5229,则x=? (2) 若log(3)2=a,用a表示代数式log(2)12=?

(1)
lg3=0.4771
lgx=-3.5229
=-4+0.4771
=-4+lg3
=lg10^(-4)+lg3
=lg3×10^(-4)
所以
x=3×10^(-4)
(2)
log(3)2=a
log(2)12
=log(2)(2²×3)
=log(2)2²+log(2)3
=2+log(2)3
=2+1/a