2x+3(2x-1)=16-(x+1)
去括号得,2x+6x-3=16-x-1,
移项得,2x+6x+x=16-1+3,
合并同类项得,9x=18,
系数化为1得,x=2.
(安徽省马鞍山市2009届高三第一次教学质量检测)If you are the thunderstorm,you’d better stay in the low-lying areas
A.unlucky enough to be caught in
B.enough unlucky to be caught in
C.to be caught unlucky enough in
D.to be enough unlucky caught in
在利用动滑轮将重为10N的重物提升10cm,若拉力做的功是1.2J,所做的额外功是______,机械效率是______.