已知3^x=4^y=36,求x+2y/xy的值

问题描述:

已知3^x=4^y=36,求x+2y/xy的值

lg3^x=lg4^y=lg36
xlg3=ylg4=2lg6
x=2lg6/lg3
y=2lg6/lg4=2lg6/(2lg2)=lg6/lg2
(x+2y)/(xy)=1/y+2/x
=lg2/lg6+2/(2lg6/lg3)
=lg2/lg6+lg3/lg6
=(lg2+lg3)/lg6
=1