Question

[Nguyễn Khánh Huyền]

1 phan tich

A=(x+1)(x+2)(x+3)(x+4)-24

B=\(\left(x^2+3x+2\right)\left(x^2+7x+120-24\right)\)

C=\(\left(x-2\right)\left(x-4\right)\left(x+6\right)\left(x-8\right)+16\)

D=\(\left(x^3+3x+2\right)\left(x^2+7x+12\right)-11\)

Answer 1

[Thắng Nguyễn]

A=(x+1)(x+2)(x+3)(x+4)-24

=(x²+5x+4)(x²+5x+6)-24

Đặt t=(x²+5x+4) ta có:

t(t+2)-24=t²+6t-2t-24

=t(t+6)-4(t+6)

=(t-4)(t+6).Thay vào ta đc:

(x²+5x+4-4)(x²+5x+4+6)=(x²+5x)(x²+5x+10) 

=x(x+5)(x²+5x+10)

B=(x²+3x+2)(x²+7x+120-24)

=(x²+3x+2)(x²+7x+96)

=(x²+2x+x+2)(x²+7x+96)

=[x(x+2)+(x+2)](x²+7x+96)

=(x+1)(x+2)(x²+7x+96)

C và D bn cx lm tương tự