Problem: If xy=34\dfrac{x}{y}=\dfrac{3}{4}yx=43, then the incorrect expression in the following is:
Answer Choices:
A. x+yy=74\dfrac{x+y}{y}=\dfrac{7}{4}yx+y=47
B. yy−x=41\dfrac{y}{y-x}=\dfrac{4}{1}y−xy=14
C. x+2yx=113\dfrac{x+2 y}{x}=\dfrac{11}{3}xx+2y=311
D. x2y=38\dfrac{x}{2 y}=\dfrac{3}{8}2yx=83
E. x−yy=14\dfrac{x-y}{y}=\dfrac{1}{4}yx−y=41 Solution:
x=34y∴x−yy=−14∴(E)x=\dfrac{3}{4} y \quad \therefore \dfrac{x-y}{y}=-\dfrac{1}{4} \quad \therefore(\mathrm{E})x=43y∴yx−y=−41∴(E) is incorrect.