ab(x2-y2)+xy(a2-b2)

ab(x2-y2)+xy(a2-b2)
ab(x2-y2)+xy(a2-b2)

ab(x2-y2)+xy(a2-b2)
原式
=abx^2-aby^2+xya^2-xyb^2
=abx^2+a^2xy-(by^2a+b^2xy)
=ax(bx+ay)-by(ay+bx)
=(ax-by)(ay+bx)

ab(x²-y²)+xy(a²-b²)
=abx²-aby²+a²xy-b²xy

如果题目是因式分解，则
ab(x²-y²)+xy(a²-b²)
=abx²-aby²+a²xy-b²xy
=ax(bx+ay)-by(bx+ay)
=(bx+ay)(ax-by)