(1)A27+A36+A64+A73=4×A1+196d=2×(A1+98d)+2A1=2×A99+2A1=224;(2)A3+A7=2A1+8d=-2……① A4×A6=A1^2+8A1×d+15d^2=-15……②可得A1=-5，d=1，然后就行了吧~
