A:of receiving
B:to receiving
C:to hearing from
D:to hear from
如图,在直角梯形ABCD中,动点P从点B出发,沿BC→CD运动至点D停止.设点P运动的路程为x,△APB的面积为y,如果y关于x的函数图象如图2所示,则△BCD的面积是( )
化简:x+1﹣x2+2xx+1=____