.已知线段AB,在AB的延长线上取一点C,使AC=2BC,在AB的反向延长线上取一点D,使DA=4AB,则线段DB是线段AC的 ▲ 倍.
因式分解:3a+12a2+12a3=_________.
分解因式:16﹣8(x﹣y)+(x﹣y)2=_________.
因式分解:x3y2﹣x5=_________.
分解因式:ax2﹣2ax+a=_________.
分解因式:m2﹣1=_________.