【简答题】若方程组 x 2 + y 2 =34 x-y=6 的解为 x= x 1 y= y 1 , x= x 2 y= y 2 求:(1) x 21 + x 22 (2) 1 y 1 + 1 y 2 .
【简答题】选择适当的词填空。 How old, How many, How, What colour, What is 1. ___________ are you? 2. ___________ ___________ books? 3. ___________ ___________ are you? 4. ___________ ___________ her name? 5. ___________...
【单选题】已知点(x 1 ,y 1 ),(x 2 ,y 2 )均在抛物线y=x 2 -1上,下列说法中正确的是( )
B.
若x 1 =-x 2 ,则y 1 =-y 2
C.
若0<x 1 <x 2 ,则y 1 >y 2
D.
若x 1 <x 2 <0,则y 1 >y 2
【简答题】若X 1 ~X 2 ,Y 1 ~Y 2 ,且X 1 ∩Y 1 =X 2 ∩Y 2 = ,证明: X 1 ∪Y 1 ~X 2 ∪Y 2 .
【简答题】选词填空。 down lost go stop 1. When the traffic light is red, we must _____________. 2. When the traffic light is green, we can _____________. 3. I'm _____________. Where's the hotel? 4. Go...
【简答题】Look and answer. (看图,回答问题) 1 . How do you feel? ____________________________________ 2. How do they feel? ____________________________________ 3. What's the matter with him? __________________________...