指数式的变化技巧

1化为同底数例1已知25^(x)=2000,80^(y)=2000,求1/x+1/y.解由25^(x)=2000,80^(y)=2000,可得(25^(x))^(y)=2000^(y),(80^(y))^(x)=2000^(x),即25^(xy)=2000^(y),80^(xy)=2000^(x),二式相乘得2000^(xy)=2000^(x+y),所以xy=x+y,所以1/x+1/y=(x+y)/xy=1.