minh lam 2 cau dau da nhe , khi nao co de dung lam tiep
ko ghi lai de nha
1.
(x−1)(x+6)(x+2)(x+3)+32
=(x2+5x−6)(x2+5x+6)+32
=(x2+5x)2−36+32
=(x2+5x)2−4
=(x2+5x−2)(x2+5x+2)
2.
(a+1)(a+4)(a+2)(a+3)+1
=(a2+5x+4)(a2+5x+6)+1
=(a2+5x+5−1)(a2+5x+5+1)+1
=(a2+5x+5)2−1+1
=(a2+5x+5)2
4
ban tu nhan da thuc nhe , ket qua la tung nay
x4+4x3+13x2+18x+20
=x4+2x3+2x3+5x2+4x2+4x2+10x+8x+20
=(x4+2x3+5x2)+(2x3+4x2+10x)+(4x2+8x+20)
=x2(x2+2x+5)+2x(x2+2x+5)+(4(x2+2x+5)
=(x2+5x+5)(x2+2x+4)