- 对数函数
- 共8722题
(1)化简:4a23b-13÷(-a-13b-13);
(2)求值:(lg5)2+lg2×lg50.
正确答案
(1)4a23b-13÷(-a-13b-13)=-6a23-(-13)b-13-(-13)=6a;
(2)(lg5)2+lg2×ig50=(lg5)2+lg2(1+lg5)=(lg5)2+lg2lg5+lg2=lg5(lg5+lg2)+lg2
=lg5+lg2=1.
不用计算器求下列各式的值:
(1)(×
)6+(
)43-4(
)-12-
×80.25-(-2009)°;
(2)log2.56.25+lg0.01+ln-21+log23.
正确答案
(1)原式=(213×312)6+()43-4×[(
)2]-12-214•23×14-1
=23•33+234•43-4×()-1-2-2=108+2-7-3=100(6分)
(2)原式=2-2+-2×3(9分)
=-(12分)
计算
(1)lg20-lg2-log23•log32+2log
(2)(-1)0+(
) -12+(
) -43.
正确答案
(1)原式=lg-
•
+
=1-1+
=
;
(2)原式=1+()2×(-12)+232×(-43)
=1++2-2
=1++
=2.
求值:
(1)(lg5)2+lg2•lg50;
(2)(2)12-(-9.6)0-(3
)-23+(1.5)-2.
正确答案
(1)(lg5)2+lg2•lg50
=(lg5)2+lg2•(lg5+1)
=(lg5)2+lg2•lg5+lg2
=lg5(lg5+lg2)+lg2
=lg5+lg2
=1.
(2)(2)12-(-9.6)0-(3
)-23+(1.5)-2
=(
9
4
)12-1-(
27
8
)-23+(
2
3
)2
=-1-(
2
3
)2+(
2
3
)2
=.
计算:
(1)2-12++
-
(2)log225•log3•log5
.
正确答案
(1)=2-12++
-
=2-12+2-12++1-1
=2•2-12+
=+
=2
(6分)
(2)=log252•log32-4•log53-2
=•
•
=16(6分)
eln2+(0.001)-13+(-1)0=______.
正确答案
解eln2+(0.001)-13+(
2-1
)0=2+(
1
1000
)-13+1= 2+(10-3)-13+1 =2+10(-3)×(-13)+1 =2+10+1=13
故答案为:13
log2+2-12•
=______.
正确答案
log2+2-12•
=
+
•
=+1=
故答案为:
计算:
(1)2723+16-12-()-2-(
)-23+lg
-3log32
(2)log2×log3
×log5
.
正确答案
(1)式子=33×23+42×(-12)-2(-1)×(-2)-(
2
3
)3×(-23)+lg10-2-2
=9+-4-
-2-2=-1.
(2)式子=×
×
=-12
×
×
=-12.
计算:
(1)(2)0+2-2×(
)-1-10012
(2)lg2+lg5+log2.56.25+lg+ln
.
正确答案
(1)(2)0+2-2×(
)-1-10012=1+
×4-
=2-10=-8.
(2)lg2+lg5+log2.56.25+lg+ln
=lg10+
+lg10-2+lne12=1+2-2+
=
.
(1)求值:lg52+lg8+lg5•lg20+(lg2)2
(2)求值:(0.0081)-14-[3×(
7
8
)0]-1×[81-0.25+(3
3
8
)-13]-12-10×0.02713.
正确答案
(1)lg52+lg8+lg5•lg20+(lg2)2
=2lg5+lg23+lg5(1+lg2)+(lg2)2
=2lg5+2lg2+lg5(1+lg2)+(lg2)2=2(lg5+lg2)+lg5+lg5•lg2+(lg2)2
=2+lg5+lg2(lg5+lg2)=3.
(2)(0.0081)-14-[3×()0]-1×[81-0.25+(3
)-13]-12-10×0.02713
=((0.3)4)-14-3-1×[(34)-14+()-1]-12-10×((0.3)3)13
=-
(
+
)-12-10•0.3
=-
-3
=0.
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