lgx+lgy=2lg(x-2y)lg(xy)=lg(x-2y)²xy=(x-2y)²解得:x=y或者x=4y那么log以根号2为底(x/y)=0或者log以根号2为底(x/y)=4
lgx+lgy=2lg(x-2y),lg(xy)=lg((x-2y)^2)xy=x^2-4xy+4y^2x^2-5xy+4y^2=0(x-y)(x-4y)=0x=y或x=4y( 舍去)x/y=1log以根号2为底(x/y)的对数=0