题目内容
不用计算器求下列各式的值.
(1)(2
)
-(-9.6)0-(3
)-
+(1.5)-2;
(2)lg2•lg50+lg5•lg20-lg100•lg5•lg2.
(1)(2
1 |
4 |
1 |
2 |
3 |
8 |
2 |
3 |
(2)lg2•lg50+lg5•lg20-lg100•lg5•lg2.
分析:(1)通过指数的运算性质求解即可.
(2)利用对数的运算性质求解即可.
(2)利用对数的运算性质求解即可.
解答:解:(1)(2
)
-(-9.6)0-(3
)-
+(1.5)-2
=(
)
-1-(
)-
+(
)-2
=
-1-(
)-2+(
)-2
=
;
(2)lg2•lg50+lg5•lg20-lg100•lg5•lg2
=lg2•(lg5+1)+lg5•(2lg2+lg5)-2lg5•lg2
=lg2lg5+lg2+lg5lg5
=lg5(lg2+lg5)+lg2
=lg5+lg2
=1.
1 |
4 |
1 |
2 |
3 |
8 |
2 |
3 |
=(
9 |
4 |
1 |
2 |
27 |
8 |
2 |
3 |
3 |
2 |
=
3 |
2 |
3 |
2 |
3 |
2 |
=
1 |
2 |
(2)lg2•lg50+lg5•lg20-lg100•lg5•lg2
=lg2•(lg5+1)+lg5•(2lg2+lg5)-2lg5•lg2
=lg2lg5+lg2+lg5lg5
=lg5(lg2+lg5)+lg2
=lg5+lg2
=1.
点评:本题考查指数的运算性质与对数的运算性质的应用,考查计算能力.

练习册系列答案
相关题目