①④
∵a+(b*c)=a+
,(a+b)*(a+c)=
= a+
,
a*(b+c)=
,∴a+(b*c)=(a+b)*(a+c),即①式正确,②式错误.
又∵a*(b+c)=
,a*b+a*c=
+
=
,
(a+b)*c=
,∴a*(b+c)=(a+b)*c,即④式正确,③式错误.
①④
∵a+(b*c)=a+
,(a+b)*(a+c)=
= a+
,
a*(b+c)=
,∴a+(b*c)=(a+b)*(a+c),即①式正确,②式错误.
又∵a*(b+c)=
,a*b+a*c=
+
=
,
(a+b)*c=
,∴a*(b+c)=(a+b)*c,即④式正确,③式错误.