#)Giải :

\(x^3-2x-4\)

\(=x^3+2x^2-2x^2+2x-4x-4\)

\(=x^3+2x^2+2x-2x^2-4x-4\)

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

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

\(x^4+2x^3+5x^2+4x-12\)

\(=x^4+x^3+6x^2+x^3+x^2+6x-2x^2-2x-12\)

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

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

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

Câu 1.

Đoán được nghiệm là 2.Ta giải như sau:

\(x^3-2x-4\)

\(=x^3-2x^2+2x^2-4x+2x-4\)

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

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

cảm ơn nha!

Em ko biết, em năm nay mới lên lớp 5 thôi.

Ta có

2x²-5x+3=2x²-2x-3x+3

=2x(x-1)-3(x-1)

=(2x-3)(x-1)

\(2x^2-5x+3=2x^2-2x-3x+3=2x\left(x-1\right)-3\left(x-1\right)=\left(x-1\right)\left(2x-3\right)\)

A=2x^3-x^2+5x+3

= (2x+1).(x² - x + 3)

\(A=2x^3-x^2+5x+3\)

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

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

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

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

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

= 2x^2 - x + 6x - 3

= x(2x - 1) + 3(2x - 1)

= (x + 3)(2x - 1)

\(2x^2+5x-3\)

\(=2x^2+6x-x-3\)

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

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

\(=2x^2+6x-x-3\)

=(x+3)(2x-1)

a) xy+3x-7y-21

=x(y+3)-7(x+3)

=(x-7)(y+3)

b)2xy-15-6x-5y

=2x(y-3)-5(-3+y)

=(2x-5)(y-3)

c)2x^2y+2xy^2-2x-2y

=2x(xy-1)+2y(xy-1)

=(2x+2y)(xy-1)

x(x+3)-5x(x-5)-5(x+3)

=(x-5)(x+3)-5x(x-5)

=(x-5)(x+3-5x)

Câu cuối mình bị nhầm dòng cuối phải là (x-5)(x+3+x-5)=(x-5)(2x-2)nha bạn

a) xy+3x-7y-21=(xy+3x)-(7y+21)= x(y+3)-7(y+3)=(y+3)(x-7)

b)2xy-15-6x+5y=(2xy-6x)+(5y-15)=2x(y-3)+5(y-3)=(y-3)(2x+5)

c)2x^2y+2xy^2-2x-2y=2xy(x+y)-2(x+y)=2(x+y)(xy-1)

d) x(x+3)-5x(x-5)-5(x+3)=[x(x+3)-5(x+3)]-5x(x-5)=(x+3)(x-5)-5x(x-5)=(x-5)(x+3-5x)=(x-5)(3-4x)

\(-2x^2+5x+3\)

\(=-2x^2+6x-x+3\)

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

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

`#3107.101107`

a)

`A = 2x^2 + 5x^3 + x^2y`

`= x^2 * (2 + 5x + y)`

b)

`5x(x - 1) + 15(x - 1)`

`= (5x + 15)(x - 1)`

`= 5(x + 3)(x - 1)`

\(a)A=2x^2+5x^3+x^2y\\=x^2(2+5x+y)\\=x^2(5x+y+2)\\---\\b)5x(x-1)+15(x-1)\\=(5x+15)(x-1)\\=5(x+3)(x-1)\)

\(Toru\)