(1)
(-2ac2)/(14a2bc)
=-c/7ab
=-c/7ab
(2)
(4-a2)/(a2-2a)
=(22-a2)/a(a-2)
=(2+a)(2-a)/-a(2-a)
=2+a/-a
=-2+a/a
(3)
(x2-16)/2x+8
=(x2-42)/2(x+4)
=(x+4)(x-4)/2(x+4)
=x-4/2
4.
(x2-16)/8-2x,其中x=-2
(x2-16)/8-2x
=(x2-42)/2(4-x)
=(x+4)(x-4)/-2(x-4)
=x+4/-2
=-x+4/2
=--2+4/2
=-2/2
=-1