b mk thấy nó sai đề sao ý 

c) \(C=\left(x^2+x+4\right)^2+8x\left(x^2+x+4\right)+15x^2\)

\(=\left(x^2+x+4\right)^2+2.4x.\left(x^2+x+4\right)+16x^2-x^2\)

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

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

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

Lời giải:

a. 

$(xy)^2-xy-2=(x^2y^2+xy)-(2xy+2)$

$=xy(xy+1)-2(xy+1)=(xy+1)(xy-2)$

b. Bạn xem lại đoạn $-16x^2$ là dấu - hay + vậy?

a) x² + 4x + 3

= x² + 3x + x +3

= ( x² + 3 ) + ( x + 3 )

= x ( x + 3 ) + ( x + 3 )

= ( x + 3 ) ( x + 1 )

b) 4x² - 4x - 3

= 4x² + 2x - 6x - 3

= ( 4x² + 2x ) - ( 6x + 3 )

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

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

c) x² - x - 12

= x² + 3x - 4x - 12

= ( x² + 3x ) - ( 4x + 12 )

= x ( x + 3 ) - 4 ( x + 3 )

= ( x + 3 ) ( x - 4 )

d) 4x⁴ - 4x²y² - 8y⁴

= 4 ( x⁴ - x²y² - 2y⁴ )

Hk tốt

cảm ơn bạn

a) \(x^2+4x+3\)

= \(x^2+x+3x+3\)

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

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

b) \(4x^2-4x-3\)

= \(4x^2+2x-6x-3\)

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

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

c)\(x^2-x-12\)

= \(x^2-4x+3x-12\)

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

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

câu d la 4x^2.y^2 phai ko

\(4x^4-4x^2y^2-8y^4\)

= \(4x^4-8x^2y^2+4x^2y^2-8y^4\)

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

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

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

Kết bạn với mình nha

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

b)\(\left(1-2a+a^2\right)-\left(b^2-2bc+c^2\right)=\left(1-a\right)^2-\left(b-c\right)^2=\)\(\left(1-a+b-c\right)\left(1-a-b+c\right)\)

lm tiếp câu c

c)  \(C=\left(x-7\right)\left(x-5\right)\left(x-4\right)\left(x-2\right)-72\)

\(=\left[\left(x-7\right)\left(x-2\right)\right]\left[\left(x-5\right)\left(x-4\right)\right]-72\)

\(=\left(x^2-9x+14\right)\left(x^2-9x+20\right)-72\)

Đặt   \(x^2-9x+17=a\) ta có:

        \(C=\left(a-3\right)\left(a+3\right)-72\)

            \(=a^2-9-72\)

           \(=a^2-81=\left(a-9\right)\left(a+9\right)\)
Thay trở lại ta được:  \(C=\left(x^2-9x++8\right)\left(x^2-9x+26\right)\)

B1: a)\(xy\left(3x-2y\right)-2xy^2=3x^2y-2y^2x-2xy^2=3x^2y-4xy^2\)

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

\(\dfrac{2\left(x-1\right)}{x^2}.\dfrac{x}{\left(x-1\right)}=\dfrac{2\left(x-1\right)x}{x^2\left(x-1\right)}=\dfrac{2}{x}\)

B2:

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

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

Mấy bài này là mấy bài rất rất rất cơ bản, học sinh TB cũng phải tự làm được, mấy bài kiểu này đừng nên đăng lên hỏi nha:vv

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

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

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

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

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

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

a.x²-2x-4y²-4y=(x²-4y²)-(2x+4y)=(x-2y)(x+2y)-2(x+2y)=(x+2y)(x-2y-2)

b.x⁴+2x³-4x-4=(x⁴-4)+(2x³-4x)=(x²-2)(x²+2)+2x(x²-2)=(x²-2)(x²+2x+2)

c.x²(1-x²)-4-4x²= -x⁴-3x²-4=x²-(x⁴+4x²+4)=x²-(x²+2)²=(x-x²-2)(x+x²+2)