49﹙x-y﹚²-25﹙x+y﹚²怎么因式分解?4（6x-y)(x-6y)

49﹙x-y﹚²-25﹙x+y﹚²怎么因式分解?4（6x-y)(x-6y)
49﹙x-y﹚²-25﹙x+y﹚²怎么因式分解?
4（6x-y)(x-6y)

49﹙x-y﹚²-25﹙x+y﹚²怎么因式分解?4（6x-y)(x-6y)
49(x-y)²-25(x+y)²
=[7(x-y)]² - [5(x+y)]²
=[7(x-y) + 5(x+y)] · [7(x-y) - 5(x+y)]
=(12x - 2y) · (2x -12y)
=4(6x-y)(x-6y)

原式=[7(x-y)+5(x+y)][7(x-y)-5(x+y)]
=(12x-2y)(2x-12y)
=4(6x-y)(x-6y)