令a=5^[log5(3)] 两边取以5为底的对数 log5(a)=log5{5^[log5(3)]} log5(a)=[log5(3)]×log5(5) log5(a)=[log5(3)]×1 log5(a)=log5(3) 所以a=3 即5^[log5(3)]=3
