=a？ -(3b)？

=(a+3b)(a-3b)

Solution (2)-16m? +(m-n)？

=(m-n)？ - 16m？

=(m-n)？ -(4m)？

=[(m-n)+4m][(m-n)-4m]

=(5m-n)(-3m-n)

=-(5m-n)(3m+n)

Solution (3) (x-2y)? -4(2x-y)？

=(x-2y)？ -[2(2x-y)]？

=[(x-2y)+2(2x-y)][(x-2y)-2(2x-y)]

=(x-2y+4x-2y)(x-2y-4x+2y)

=-3 times (5 times -4 times)

Solution (4) a? (x-y)-b？ (x-y)

=(x-y)(a？ -B? )

=(x-y)(a+b)(a-b)

The solution (5)16m4-n 4 represents a power.

=(4m？ )-(n？ )?

=(4m？ +n？ )(4m？ -n？ )

=(4m？ +n？ )(2m+n)(2m-n)

Solution (6) (a+b+c+d)? -(a-b+c-d)？

=[(a+b+ c+d)+(a-b+ c-d)][(a+b+ c+d)-(a-b+ c-d)]

=(a+b+ c+d+a-b+ c-d)(a+b+ c+d-a+B- c+d)

=(2a+2c(2b+2d)

=4(a+c)(b+d)