题目

When I walk through the streets, I pass strange rooms where people are doing strange things. Some are biking madly. Others are holding metal bars to keep them from dropping down. Still others are jumping around while someone is shouting at them. It looks like something out of Dante’s Inferno (但丁《神曲》中的《地狱篇》). But what is the most amazing is that people pay for these sufferings! The strange rooms are gyms. It is reported that some 41 million Americans are gym members. 12% of the memberships are born in January, as they are determined to knock off the holiday fa已知x=-1是方程ax2+bx+c=0的根，则a、b、c必须满足________．