y=ax^2+bx+c的图象经过原点,c=0
开口向下,a1,b>-2a>0,b+2a>0,b+a>-a>0
p=|a-b+c|+|2a+b|
=|a-b|+|2a+b|
=b-a+2a+b=a+2b
Q=|a+b|+|2a-b| (2a-b