问题
解答题
计算下列各式的值. (1)3
(2)32+log35; (3)71-log75; (4)4
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答案
(1)原式=3
log1 2
4=3log3
2=32log32=3log322=3log34=4.3
(2)原式=32+log35=32⋅3log35=9×5=45.
(3)原式=71-log75=7log7
=7 5
.7 5
(4)4
(log29-log25)=22×1 2
(log21 2
)=2log29 5
=9 5
.9 5