a)\(x\left(x+1\right)\left(x+2\right)\left(x+3\right)+1=\left(x^2+3x\right)\left(x^2+3x+2\right)+1\)

Đặt \(t=x^2+3x\) thì biểu thức có dạng \(t\left(t+2\right)+1=t^2+2t+1=\left(t+1\right)^2=\left(x^2+3x+1\right)^2\)

b)\(\left(x^2-x+2\right)^2+4x^2-4x-4=\left(x^2-x+2\right)^2+4\left(x^2-x-1\right)\)

Đặt \(k=x^2-x+2\) thì biểu thức có dạng

k²+4(k-3)=k²+4k-12=k²-2k+6k-12=k(k-2)+6(k-2)=(k-2)(k+6)=(x²-x)(x²-x+8)=(x-1)x(x²-x+8)

c)làm tương tự câu a

`b)x^3+y^3+z^3-3xyz`

`=x^3+3xy(x+y)+z^3-3xy(x+y)-3xyz`

`=(x+y)^3+z^3-3xy(x+y+z)`

`=(x+y+z)[(x+y)^2-z(x+y)+z^2]-3xy(x+y)`

`=(x+y+z)(x^2+2xy+y^2-zx-yz-3xy+z^2)`

`=(x+y+z)(x^2+y^2+z^2-xy-yz-zx)`

giúp mk vs mk cần gấp T^T

Bạn xem lại đề câu b) nhé đề đúng là `x^3+y^3+z^3-3xyz`.Còn được thì xem lại câu c) nhé do số quá xấu.

`a)x^4+3x^3-6x^2-8`

`=x(x^3+3x^2-6x-8)`

`=x[(x-2)(x^2+2x+4)+3x(x-2)]`

`=x(x-2)(x^2+5x+4)`

`=x(x-2)(x^2+x+4x+4)`

`=x(x-2)(x+1)(x+4)`

`c)(x+1)(x+3)(x+5)(x+7)-5`

`=[(x+1)(x+7)][(x+3)(x+5)]-5`

`=(x^2+8x+7)(x^2+8x+15)-5`

`=(x^2+8x+11)^2-4^2-5`

`=(x^2+8x+11)^2-21`

`=(x^2+8x+11-sqrt21)(x^2+8x+11+sqrt21)`

\(a)x^5+x^4+1\)

\(=x^3\left(x^2+x+1\right)-\left(x-1\right)\left(x^2+x+1\right)\)

\(=\left(x^2+x+1\right)\left(x^3-x+1\right)\)

\(b)x^8+x^7+1\)

\(=\left(x^8-x^2\right)+\left(x^7-x\right)+\left(x^2+x+1\right)\)

\(=\left(x^2+x+1\right)\left(x^6-x^4+x^3-x+1\right)\)

\(#Tuyết\)

a) \(\left(x+1\right)\left(x+2\right)\left(x+3\right)\left(x+4\right)-15\left(1\right)=\left[\left(x+1\right)\left(x+4\right)\right]\left[\left(x+2\right)\left(x+3\right)\right]-15=\left(x^2+5x+4\right)\left(x^2+5x+6\right)-15\)

Đặt \(t=x^2+5x+4\)

(1) trở thành: \(t\left(t+2\right)-15=t^2+2t+1-16=\left(t+1\right)^2-4^2=\left(t-3\right)\left(t+5\right)\)

Thay t: \(\left(x+1\right)\left(x+2\right)\left(x+3\right)\left(x+4\right)-15=\left(x^2+5x+4-3\right)\left(x^2+5x+4+5\right)=\left(x^2+5x+1\right)\left(x^2+5x+9\right)\)

b) \(\left(2x+5\right)^2-\left(x-9\right)^2=\left(2x+5-x+9\right)\left(2x+5+x-9\right)=\left(x+14\right)\left(3x-4\right)\)

a: Ta có: \(\left(x+1\right)\cdot\left(x+2\right)\left(x+3\right)\left(x+4\right)-15\)

\(=\left(x^2+5x+4\right)\left(x^2+5x+6\right)-15\)

\(=\left(x^2+5x\right)^2+10\left(x^2+5x\right)+24-15\)

\(=\left(x^2+5x\right)^2+10\left(x^2+5x\right)+9\)

\(=\left(x^2+5x+1\right)\left(x^2+5x+9\right)\)

b: \(\left(2x+5\right)^2-\left(x-9\right)^2\)

\(=\left(2x+5-x+9\right)\left(2x+5+x-9\right)\)

\(=\left(x+15\right)\left(3x-4\right)\)

a) Sửa đề: \(a^2x+a^2y-7x-7y\)

\(=a^2\left(x+y\right)-7\left(x+y\right)=\left(x+y\right)\left(a^2-7\right)\)

b) \(=\left(2x-3y\right)\left(2x+3y\right)+2\left(2x-3y\right)=\left(2x-3y\right)\left(2x+3y+2\right)\)

\(c,Sửa:x^2-2x+2y-y^2=\left(x-y\right)\left(x+y\right)-2\left(x-y\right)=\left(x-y\right)\left(x+y-2\right)\\ d,=\left(4x^4+36x^2+81\right)-36x^2\\ =\left(2x^2+9\right)^2-36x^2=\left(2x^2-6x+9\right)\left(2x^2+6x+9\right)\\ e,=x^7+x^6-x^6+x^5-x^5+x^4-x^4+x^3-x^3+x^2-x^2+x^2+x-x+1\\ =x^5\left(x^2+x+1\right)-x^4\left(x^2+x+1\right)+x^2\left(x^2+x+1\right)-x\left(x^2+x+1\right)+\left(x^2+x+1\right)\\ =\left(x^2+x+1\right)\left(x^5-x^4+x^2-x+1\right)\)

a.

\(=\left(x+1\right)^3-\left(3z\right)^3\)

\(=\left(x+1+3z\right)\left[\left(x+1\right)^2+3z\left(x+1\right)+9z^2\right]\)

\(=\left(x+3z+1\right)\left(x^2+2x+1+3zx+3z+9z^2\right)\)

b.

\(=\left(x-y\right)^2-z\left(x-y\right)\)

\(=\left(x-y\right)\left(x-y-z\right)\)

c.

\(=x^4-1+4x^2-4\)

\(=\left(x^2-1\right)\left(x^2+1\right)+4\left(x^2-1\right)\)

\(=\left(x^2-1\right)\left(x^2+5\right)\)

\(=\left(x-1\right)\left(x+1\right)\left(x^2+5\right)\)

a) Ta có: \(x^3+3x^2+3x+1-27z^3\)

\(=\left(x+1\right)^3-\left(3z\right)^3\)

\(=\left(x+1-3z\right)\left(x^2+2x+1+3xz+3z+9z^2\right)\)

b) Ta có: \(x^2-2xy+y^2-zx+yz\)

\(=\left(x-y\right)^2-z\left(x-y\right)\)

\(=\left(x-y\right)\left(x-y-z\right)\)

c) Ta có: \(x^4+4x^2-5\)

\(=x^4+4x^2+4-9\)

\(=\left(x^2+2\right)^2-3^2\)

\(=\left(x^2-1\right)\left(x^2+5\right)\)

\(=\left(x-1\right)\left(x+1\right)\left(x^2+5\right)\)

a)

\(x^4+1996x^2+1995x+1996\)

\(=\left(x^4-x\right)+\left(1996x^2+1996x+1996\right)\)

\(=x\left(x^3-1\right)+1996\left(x^2+x+1\right)\)

\(=x\left(x-1\right)\left(x^2+x+1\right)+1996\left(x^2+x+1\right)\)

\(=\left(x^2+x+1\right)\left[x\left(x-1\right)+1996\right]\)

\(=\left(x^2+x+1\right)\left(x^2-x+1996\right)\)

b)

\(x^4+1997x^2+1996x+1997\)

\(=\left(x^4-x\right)+\left(1997x^2+1997x+1997\right)\)

\(=x\left(x^3-1\right)+1997\left(x^2+x+1\right)\)

\(=x\left(x-1\right)\left(x^2+x+1\right)+1997\left(x^2+x+1\right)\)

\(=\left(x^2+x+1\right)\left[x\left(x-1\right)+1997\right]\)

\(=\left(x^2+x+1\right)\left(x^2-x+1997\right)\)

x⁴+1996x²+1995x+1996

=(x^4_x)+(1996x²+1996x+1996)

=x(x³-1)+1996(x²+x+1)

=x(x-1)(x²+x+1)+1996(x²+x+1)

=(x²+x+1)((x²-1)+1996)

=(x²+x+1)((x+1)(x-1)+1996)

Câu 2 tương tự bạn nhé!

Bạn ơi lúc nãy mk làm là sai rồi !!Sai ở dòng thứ 4

Câu 1:

a: Sửa đề: \(A=\left(x+2\right)\left(x^2-2x+4\right)+x\left(1-x\right)\left(1+x\right)\)

\(=x^3+2^3+x\left(1-x^2\right)\)

\(=x^3+8+x-x^3\)

=x+8

b: Khi x=-4 thì A=-4+8=4

c: Đặt A=-2

=>x+8=-2

=>x=-10

Câu 2:

a: \(x^3-3x^2=x^2\cdot x-x^2\cdot3=x^2\left(x-3\right)\)

b: \(5x^3+10x^2+5x\)

\(=5x\cdot x^2+5x\cdot2x+5x\cdot1\)

\(=5x\left(x^2+2x+1\right)\)

\(=5x\left(x+1\right)^2\)