题目内容
(1)计算:(
)6-
×(
)
-(-2013)0
(2)已知log73=a,log74=b,用a,b表示log4948.
3 | 2 |
7 |
5 |
25 |
49 |
1 |
2 |
(2)已知log73=a,log74=b,用a,b表示log4948.
(1)(
)6-
×(
)
-(-2013)0
=2
-
×
-1
=2-1-1
=0.
(2)∵log73=a,log74=b,
∴log4948=
log7(3×16)
=
(log73+log716)
=
(log73+2log74)
=
(a+2b).
3 | 2 |
7 |
5 |
25 |
49 |
1 |
2 |
=2
6 |
3 |
7 |
5 |
5 |
7 |
=2-1-1
=0.
(2)∵log73=a,log74=b,
∴log4948=
1 |
2 |
=
1 |
2 |
=
1 |
2 |
=
1 |
2 |
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