Find "a" the identity element and "b" inverse for the operation d_英语解答

Find "a" the identity element and "b" inverse for the operation defined as "a*b=a+b+2"星号不是乘号····

人气：350 ℃　时间：2020-02-05 13:34:08

解答

令a+b+2=a得b=-2,所以-2是单位元
ab=a+b+2=-2,b=-4-a,所以a的逆元为-4-a