一般地;两条平行线l1:Ax+By+C1=0和l2:Ax+By+C2=0间的距离公式是d= |C1−C2|A2+B2 如:求:两条平行线x+3y﹣4=0和2x+6y﹣9=0的距离.
解:将两方程中x,y的系数化成对应相等的形式,得2x+6y﹣8=0和2x+6y﹣9=0,因此,d= |−8+9|22+62=1020 两条平行线l1:3x+4y=10和l2:6x+8y﹣10=0的距离是____.
Mrs Smith's living room is large. There is a television in the room. The television is near the window. There are some magazines on the television. There is a table in the room. There are some newspapers on the table. There are some armchairs in the room. The armchairs are near the table. There is a stereo in the room. The stereo is near the door. Mrs Smith often listens to music from it.
下面关于音调和响度的说法中正确的是( )
下列句子标点符号使用不恰当的一项是 ( )
已知一次函数y=kx+b的图象如图所示,当y>0时,x的取值范围是( )