1) 3x^2 +7x-6

=3x²-2x+9x-6

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

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

2)6x^213x+6

đề khùng

3)8x^2+5x+3

8x²-3x+8x+3

Đề khùng

5x²+14x-3=(5x²+15x)-(x+3)=5x(x+3)-(x+3)=(x+3)(5x-1)

5x²-18x-8=(5x²-20x)+(2x-8)=5x(x-4)+2(x-4)=(x-4)(5x+2)

6x²+7x-3=(6x²-2x)+(9x-3)=2x(3x-1)+3(3x-1)=(3x-1)(2x+3)

x²-xy-2y²=(x²-y²)-(xy+y²)=(x-y)(x+y)-y(x+y)=(x+y)(x-y-y)=(x+y)(x-2y)

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

b/ \(=x^2-3xy-2y^2\)

c/ \(=2xy-6y^2+x^2-3xy=2y\left(x-3y\right)+x\left(x-3y\right)=\left(2y+x\right)\left(x-3y\right)\)

d/ \(=xy-2y^2+2x^2-4xy=y\left(x-2y\right)+2x\left(x-2y\right)=\left(y+2x\right)\left(x-2y\right)\)

a)(x-y)(x+2y)

b) nghiệm lẻ>mìh nghĩ là sai đề

c)(x-3y)(x+2y)

d)(x-2y)(2x+y)
 

____________________________
li-ke cho mk nha bnLe Ngoc Bao Chau
 

a/ \(=2xy+6x^2-y^2-3xy=2x\left(y+3x\right)-y\left(y+3x\right)=\left(2x-y\right)\left(y+3x\right)\)

b/ \(=2x^2+5xy+y^2\)

c/ \(=-4y^2+6xy-4xy+6x^2=-2y\left(2y-3x\right)-2x\left(2y-3x\right)=\left(-2y-2x\right)\left(2y-3x\right)=-2\left(y+x\right)\left(2y-3x\right)\)

d/ \(=-4y^2-2xy+4xy+2x^2=-2y\left(2y+x\right)+2x\left(2y+x\right)=\left(-2y+2x\right)\left(2y+x\right)=-2\left(y-x\right)\left(2y+x\right)\)

x^2 + xy - 2y^2 = ( x^2 - 2xy + y^2 ) + 3xy - 3y^2 = ( x - y )^2 + 3y.( x - y ) = ( x - y )(x + 2y)

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

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

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

\(x^3-6x^2-x+30=x^3+2x^2-8x^2-16x+15x+30\)

                                       \(=x^2\left(x+2\right)-8x\left(x+2\right)+15\left(x+2\right)\)

                                       \(=\)  \(\left(x^2-8x+15\right)\left(x+2\right)\)

                                      \(=\left(x^2-5x-3x+15\right)\left(x+2\right)\)

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