(a+b-1)^2+16ab-3的绝对值=0,
a+b-1=0且16ab-3=0
a+b=1,ab=3/16
a^3b-2a^2b^2+ab^3
=ab(a²-2ab+b²)
=ab[(a+b)²-4ab]
=3/16×(1-4×3/16)
=3/64