张亦驰的回答：当x=1时,其值为负4: a*1+b*1+c=-4.....[1] 当x=7时,其值为8: 49a+7b+c=8....[2] x=5时,其值为0: 25a+5b+c=0.....[3] [2]-[1]:8a+b=2.....[4] [2]-[3]:12a+b=4.....[5] [5]-[4]:a=0.5 代入：[4]得：b=-2 代入[1]得：c=-2.5 黄静怡的回答：当x=1时,其值为负4: a*1+b*1+c=-4.....[1] 当x=7时,其值为8: 49a+7b+c=8....[2] x=5时,其值为0: 25a+5b+c=0.....[3] [2]-[1]:8a+b=2.....[4] [2]-[3]:12a+b=4.....[5] [5]-[4]:a=0.5 代入：[4]得：b=-2 代入[1]得：c=-2.5 卢斌的回答：当x=1时,其值为负4: a*1+b*1+c=-4.....[1] 当x=7时,其值为8: 49a+7b+c=8....[2] x=5时,其值为0: 25a+5b+c=0.....[3] [2]-[1]:8a+b=2.....[4] [2]-[3]:12a+b=4.....[5] [5]-[4]:a=0.5 代入：[4]得：b=-2 代入[1]得：c=-2.5 |
