数学lg加减 附图···················

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数学lg加减附图···················数学lg加减附图···················数学lg加减附图···················原式=(lg5-lg2)(lg5+lg

数学lg加减 附图···················
数学lg加减 附图················
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数学lg加减 附图···················
原式=(lg5-lg2)(lg5+lg2)÷(2(lg5-lg2))-log3 3^(1/2)
=(lg5+lg2)/2-1/2
=1/2-1/2
=0

第一个括号用平方差公式拆开;第二个括号25是5的平方,4十二的平方,将平方2提出,最后一项是1/2;最后可得答案是0