因式分解下列各數,THX

a)6xm+2ym-3xn-yn

=2m(3x+y)-n(3x+y)

=(2m-n)(3x+y)

b)7a-7b

=7(a-b)

c)-4x+32y

=-4(x-8y)

d)-3a-6b-15c

=-3(a+2b+5c)

e)2x-6bx+2ax

=2x(1-3b+a)

f)x(a-5)-y(5-a)

=x(a-5)+y(a-5)

=(x+y)(a-5)

g)(2+a)(a+b)-4a(a+b)

=(a+b)(2+a-4a)

=(a+b)(-3a+2)

=-(a+b)(3a-2)

h)-p(r-s)-5(s-r)

=p(s-r)-5(s-r)

=(p-5)(s-r)