题目内容
(1)计算:0.064-
-(-
)0+7log72+0.25
×0.5-4;
(2)已知a=lg2,10b=3,用a,b表示log6
.
1 |
3 |
1 |
8 |
5 |
2 |
(2)已知a=lg2,10b=3,用a,b表示log6
30 |
(1)原式=(
)-
-1+2+(
)
× (
)-4=(
)3×(-
)-1+2+(
)5×(
)-4=
-1+2+
=4
(2)∵10b=3
∴b=lg3
又∵a=lg2
∴log6
=
log630=
(1+log65)=
(1+
)=
(1+
)=
(1+
)=
(1+
)=
64 |
1000 |
1 |
3 |
1 |
4 |
5 |
2 |
1 |
2 |
4 |
10 |
1 |
3 |
1 |
2 |
1 |
2 |
10 |
4 |
1 |
2 |
(2)∵10b=3
∴b=lg3
又∵a=lg2
∴log6
30 |
1 |
2 |
1 |
2 |
1 |
2 |
lg5 |
lg6 |
1 |
2 |
lg
| ||
lg(2×3) |
1 |
2 |
1-lg2 |
lg2+lg3 |
1 |
2 |
1-a |
a+b |
b+1 |
2(a+b) |
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