当a>1,a^x>b 怎么推出x>log(a)b (b>0)当0当a>1,a^x>b 怎么推出x>log(a)b (b>0)当0
当a>1,a^x>b 怎么推出x>log(a)b (b>0)当0你应该看看对数的定义a^x>b ,a>1,lg(a^x)>lgb,xlga>lgb,lga>0,x>lgb/lga=loga b同理可证0
等式两边以loga为底求对数 ,a>1是增函数,0