a与b互为相反数,a+b=0,a=-ba不等于0,a可以做除数c与b互为倒数,cd=13a+5cd-a/b+3b=3(a+b)+5cd-a/b=0+5+1=6
a=-b, cd=1代入原式可得结果为6
63a+3b=05cd=5-a/b=1
