解方程:x2-2x=2.
方程的两边同时加1得,x2-2x+1=2+1,
即(x-1)2=3,
故x-1=±3,
x1=1+3,x2=1-3.
To their great ___, they got the bad news that their English teacher had been in hospital for quite a few days.
A.joy
B.disappointment
C.happiness
D.sadness
关于更换变压器的回收年限,一般考虑当计算的回收年限小于5年时,变压器()更新为宜。
A.应
B.应立即
C.不应
D.不可