Hoặc
c) 2aa2−4a+4+42−a;
c) 2aa2−4a+4+42−a
=2a(a−2)2−4a−2=2a(a−2)2−4(a−2)(a−2)2
=2a−4a+8(a−2)2=8−2a(a−2)2.