| 解方程组 （1）
（2）
|
（1）
，2x+y=11① 3x+y=12②
②-①得，x=1；
把x=1代入①得，y=11-2=9．
故此方程组的解为
；x=1 y=9
（2）
，2a+3b=2① 4a-9b=-1②
①×2-②得，b=
；1 3
把b=
代入①得，2a+1=2，解得a=1 3
．1 2
故此方程组的解为
．a= 1 2 b= 1 3
| 阅读理解。 | |
China, red can be a happy color. But in some other countries, people think that red is an angry color. Colors are sometimes called hot, cold and neutral (中性的). Red and yellow are hot colors. They make a room feel warmer. They make people feel excited. Blue and green are cold colors. They make a room feel cooler. They make people feel calm. Brown and gray are neutral colors. They don't affect (影响) our feelings. 根据短文内容，判断句子正(T)误(F)。 ( ) 1. Yellow and red are hot colors. ( ) 2. Blue and green make us feel calm. ( ) 3. Colors can affect our feelings. ( ) 4. Brown is a neutral color. ( ) 5. Color isn't important in our lives. |