logxyz a=1/loga xyz=1/(loga x+loga y+loga z)=12
logz a=1/loga z=24
logy a=1/loga y=40
logx a=1/loga x=60這道題 主要用到對數(shù)函數(shù)性質(zhì)換底公式log(a)(b)=log(c)(b)/log(c)(a)(a,c均大于零且不等于1）logz a=loga a/loga z=1/loga z其他幾個同樣的方法 log(a)(MN)=log(a)(M)+log(a)(N);