解方程:x2+7x+12=0.
x2+7x+12=0,
(x+3)(x+4)=0,
∴x+3=0,x+4=0,
x1=-3,x2=-4.
Tian'anmen Square is very ____________.[ ]
A. famous
B. small
C. farmers
如何正确理解婚姻自由?