Đáp án:
50, 2a²(x-y)-4a(y-x)
= 2a²(x - y)+4a(x - y)
=(2a² + 4a)(x - y)
= 2a(a + 2)(x - y)
51, 3ab(x - 4) + 9a(4 - x)
= 3ab(x-4) - 9a(x-4)
=(3ab-9a)(x - 4)
=3a(b-3)( x - 4)
52, -2a²(x - 1)+4a(1 - x)
= 2a²(1 - x)+4a(1 - x)
=(2a² + 4a)(1 - x)
=2a(a + 2)(1 - x)
53, a(x - 3)-a² (3 -x)
= a(x - 3) + a²(x-3)
= (a+a²)(x - 3)
=a(1+a)(x-3)
54, 2xy(a-1) - 4x²y(1-a)
= 2xy(a - 1) + 4x²y(a - 1)
=(2xy + 4x²y)(a - 1)
= 2xy ( 1 + 2x)(a - 1)
55, 5x²y(x - 7) - 5xy(7 - x )
= 5x²y(x - 7)+ 5xy (x -7)
=(5x²y + 5xy )(x - 7)
=5xy(x+1)(x - 7)
56, 3ab(x - y)+3a( y - x)
= 3ab(x-y) - 3a(x - y)
=(3ab - 3a)(x - y)
=3a(b - 1)(x - y)
57, 4a(x - 5) - 2(5 - x)
= 4a(x - 5)+2(x - 5)
=(4a + 2)(x - 5)
=2(2a+1)(x - 5)
58, -3a(x - 3) - a²(3-x)
= 3a(3-x)-a²(3-x)
=(3a-a²)(3-x)
=a(3-a)(3-x)
59. 2a²b(x+y)-4a³b(-x - y)
=2a²b(x+y)+4a³b(x+y)
=(2a²b + 4a³b)(x + y)
=2a²b(1+2a)(x + y)
60 . 7a(x-2y) - 14a²(2y-x)
=7a(x-2y)+14a²(x-2y)
=(7a+14a²)(x-2y)
=7a(1+2a)(x-2y)
