Question

求1/2lg乘以23/49-4/3lg根号下8+lg根号下245得多少?

Answer 1

(1/2)lg(23/49)-(4/3)lg√8+lg√245=

=lg(23/49)^(1/2)-lg√8^(4/3)+lg245^(1/2).

=lg{[(23/49)*245)^(1/2)]/8^[(1/2)*(4/3)]}.

=lg(23*5)^(1/2)/8^(2/3).

=lg(115^(1/2)/4.

=(1/2)lg(115/16).

∴原式=lg√(115/16).