几个指数对数题,3.(4).(a-b)÷(a1/3次方-b1/3次方)7.(3).lg^5+lg2lg50(4).(lg^5-lg^2)/(lg25-lg4)10.(2)logaX/logabX=1+logaBvcyulin谢谢你,但是不知道你审题没清楚还是我概念没理解对,第7题的(3) lg^(2)5=lg5^2
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![几个指数对数题,3.(4).(a-b)÷(a1/3次方-b1/3次方)7.(3).lg^5+lg2lg50(4).(lg^5-lg^2)/(lg25-lg4)10.(2)logaX/logabX=1+logaBvcyulin谢谢你,但是不知道你审题没清楚还是我概念没理解对,第7题的(3) lg^(2)5=lg5^2](/uploads/image/z/10446391-55-1.jpg?t=%E5%87%A0%E4%B8%AA%E6%8C%87%E6%95%B0%E5%AF%B9%E6%95%B0%E9%A2%98%2C3.%284%29.%28a-b%29%C3%B7%EF%BC%88a1%2F3%E6%AC%A1%E6%96%B9-b1%2F3%E6%AC%A1%E6%96%B9%EF%BC%897.%283%29.lg%5E5%2Blg2lg50%284%29.%28lg%5E5-lg%5E2%29%2F%28lg25-lg4%2910.%EF%BC%882%EF%BC%89logaX%2FlogabX%3D1%2BlogaBvcyulin%E8%B0%A2%E8%B0%A2%E4%BD%A0%EF%BC%8C%E4%BD%86%E6%98%AF%E4%B8%8D%E7%9F%A5%E9%81%93%E4%BD%A0%E5%AE%A1%E9%A2%98%E6%B2%A1%E6%B8%85%E6%A5%9A%E8%BF%98%E6%98%AF%E6%88%91%E6%A6%82%E5%BF%B5%E6%B2%A1%E7%90%86%E8%A7%A3%E5%AF%B9%EF%BC%8C%E7%AC%AC7%E9%A2%98%E7%9A%84%EF%BC%883%EF%BC%89+lg%5E%282%295%3Dlg5%5E2)
几个指数对数题,3.(4).(a-b)÷(a1/3次方-b1/3次方)7.(3).lg^5+lg2lg50(4).(lg^5-lg^2)/(lg25-lg4)10.(2)logaX/logabX=1+logaBvcyulin谢谢你,但是不知道你审题没清楚还是我概念没理解对,第7题的(3) lg^(2)5=lg5^2
几个指数对数题,
3.(4).(a-b)÷(a1/3次方-b1/3次方)
7.(3).lg^5+lg2lg50
(4).(lg^5-lg^2)/(lg25-lg4)
10.(2)logaX/logabX=1+logaB
vcyulin谢谢你,但是不知道你审题没清楚还是我概念没理解对,第7题的(3) lg^(2)5=lg5^2吗?
几个指数对数题,3.(4).(a-b)÷(a1/3次方-b1/3次方)7.(3).lg^5+lg2lg50(4).(lg^5-lg^2)/(lg25-lg4)10.(2)logaX/logabX=1+logaBvcyulin谢谢你,但是不知道你审题没清楚还是我概念没理解对,第7题的(3) lg^(2)5=lg5^2
对一楼进行一下补充,加上括号就明显很多!
3.
a-b=[a^(1/3)]^3-[b^(1/3)]^3=[a^(1/3)-b^(1/3)][a^(2/3)+(ab)^(1/3)+b^(2/3)] 【立方公式前面为-后面为+】
(a-b)÷(a1/3次方-b1/3次方)=a^(2/3)+(ab)^(1/3)+b^(2/3)
7
(3)(lg5)^2+lg2lg(2*5^2)=(lg5)^2+lg2(lg2+2lg5)=(lg5)^2+2lg2lg5+(lg2)^2
=(lg2+lg5)^2=(lg10)^2=1
(4)(lg^5-lg^2)/(lg25-lg4)=(lg^5-lg^2)/(2lg5-2lg2)=1/2(lg5+lg2)=1/2*lg10=1/2
3.
a-b=[a^(1/3)]^3-[b^(1/3)]^3=[a^(1/3)-b^(1/3)][a^(2/3)-(ab)^(1/3)+b^(2/3)]
(a-b)÷(a1/3次方-b1/3次方)=a^(2/3)-(ab)^(1/3)+b^(2/3)
7.
(3)lg5^2+lg2lg(2*5^2)=lg5^2+lg2(lg2+2lg5)=lg5^2+2l...
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3.
a-b=[a^(1/3)]^3-[b^(1/3)]^3=[a^(1/3)-b^(1/3)][a^(2/3)-(ab)^(1/3)+b^(2/3)]
(a-b)÷(a1/3次方-b1/3次方)=a^(2/3)-(ab)^(1/3)+b^(2/3)
7.
(3)lg5^2+lg2lg(2*5^2)=lg5^2+lg2(lg2+2lg5)=lg5^2+2lg2lg5+lg2^2
=(lg2+lg5)^2
(4)(lg^5-lg^2)/(lg25-lg4)=(lg^5-lg^2)/(2lg5-2lg2)=1/2(lg5+lg2)
10
logaX/logabX=lgX/lga/(lgX/lgab)=lgab/lga=(lga+lgb)/lga=1+lgb/lga
=1+logaB
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