在△ABC中,AB=6cm,AC=5cm,点D、E分别在AB、AC上.若△ADE与△ABC相似,且S△ADE:S四边形BCED=1:8,则AD= cm.
(a+b-1)(a-b+1)=(_____)2-(_____)2.
(-3x2+2y2)(______)=9x4-4y4.
(-2x+y)(-2x-y)=______.
若a2+2a=1,则(a+1)2=_________.
已知每辆汽车要装4个轮胎,则51只轮胎至多能装配 辆汽车.