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数学对数涵数运算急

来源:学生作业帮 编辑:拍题作业网作业帮 分类:数学作业 时间:2024/04/28 02:11:49
数学对数涵数运算


(1)原式=(1/2)*[log2 (7/48)] - (1/2)*(log2 42)+ (log2 12)
=(1/2)*[log2 (7/48) - (log2 42)]+ (log2 12)
=(1/2)*{log2 [(7/48)÷42]} + (log2 12)
=(1/2)*{log2 [1/(6*48)]} + (log2 12)
=-(1/2)*[log2 (4*9*8)] + 2+(log2 3)
=-(1/2)*(5+ log2 9)+ 2+(log2 3)
=(-5/2) - (log2 3)+ 2+(log2 3)
=-1/2
(2)原式=2lg5 + 2lg2+ lg5*(2lg2 + lg5)+(lg2)²
=2+ (lg5)²+2*lg5*lg2+(lg2)²
=2+(lg5+lg2)²
=2+1=3
再问: =(1/2)*{log2 [1/(6*48)]} + (log2 12)
               =-(1/2)*[log2 (4*9*8)] + 2+(log2 3)这一步怎么变的啊=2+ (lg5)²+2*lg5*lg2+(lg2)²
还有这里。。呜呜  都不会
再答: =(1/2)*{log2 [1/(6*48)]} + (log2 12) =(1/2)*{log2 [(6*48)的-1次幂]} + (log2 12) =-(1/2)*{log2 (6*6*8)} + (log2 12) =-(1/2)*{log2 (4*9*8)} + (log2 12) =-(1/2)*{log2 (3² *2的5次幂)} + (log2 12) 另外: =2+ (lg5)²+2*lg5*lg2+(lg2)² (是指上一步推到这步不会?还是这步推下一步不会哈?)