Question

已知25的x次方=2000,80的y次方=2000,求xy分之x加y

Answer 1

25^x=2000=80*25

25^x/25=80

25^x-1=80

80^y=2000=80*25

80^y/80=25

80^y-1=25

(80^y-1)^x-1=80

80^(y-1)(x-1)=80^1

(y-1)(x-1)=1

xy-(x+y)+1=1

xy=x+y

(x+y)/xy=1