微分方程sec2x tan ydx+sec2y tan xdy=0的通解是( )
A. tan x/ tan y=C
B. tan x tan y=C
C. tan x +tan y=C
D. tan x-tan y=C
查看答案
微分方程(ex+y-ex)dx+(ex+y+ey)dy=0的通解是( )
A. ex(ey-1)=C
B. (ex+1)ey=C
C. (ex+1)(ey-1)=C
D. (ex+1)(ey+1)=C
微分方程cos x sin ydx+sin x cos ydy=0的通解是( )
A. sin x sin y=C
B. sin x +sin y=C
C. sin x /sin y=C
D. sin x -sin y=C
______-aroma baijiu is most closely associated with Sichuan Province.
A. Strong
B. Light
C. Sauce
D. Rice
________ once said:“The daunting route into the region of Shu is more daunting than climbing the sky.”
A. Wang Anshi
B. Li Bai
C. Bai Juyi
Du Fu
微信支付 
支付宝支付