log2(根号下7/48)+log2(12)-1/2log2(42)-1=?
答案:2 悬赏:10 手机版
解决时间 2021-02-05 16:17
- 提问者网友：沉默菋噵
- 2021-02-04 20:17
log2(根号下7/48)+log2(12)-1/2log2(42)-1=?
最佳答案
- 五星知识达人网友：持酒劝斜阳
- 2021-02-04 21:29
log2[根号下(7/48)]+log2(12)-1/2log2(42)-1?
=log2{12*根号下(7/48)/[根号下(42)]}-1
=log2{12*根号下[7/(48*42)]}-1
=log2{12*根号下[7/(6*2*2*2**6*7)]}-1
=log2根号下(1/2)-1
=(1/2)log2(1/2)-1
=(1/2)log2(2^-1)-1
=(-1)(1/2)log2(2)-1
=-1/2-1
=-3/2
=log2{12*根号下(7/48)/[根号下(42)]}-1
=log2{12*根号下[7/(48*42)]}-1
=log2{12*根号下[7/(6*2*2*2**6*7)]}-1
=log2根号下(1/2)-1
=(1/2)log2(1/2)-1
=(1/2)log2(2^-1)-1
=(-1)(1/2)log2(2)-1
=-1/2-1
=-3/2
全部回答
- 1楼网友：琴狂剑也妄
- 2021-02-04 21:58
解：原式 = log2(√7/√48) + log212 – (1/2)log242 – log22 = log2√(7/48) + log212 – log2√42 – log22 = log2[√(7/48)*12/√42/2] = log2[6√(7/2016)] = log2[6√(1/288)] = log2√(36/288) = log2√(1/8) = (1/2)log22-3 = (1/2)*(-3) = -3/2 。
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