\(x^4+4x^3+2x^2-4x+1\)

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

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

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

1.A

2.C

3.B

4.C

a

c

b

c

(x-1)y^2-4(x-1)y

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

\(4x^2-3x-1=0\\ \Leftrightarrow\left(x-1\right)\left(4x+1\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=1\\x=-\dfrac{1}{4}\end{matrix}\right.\)

\(4.\left(2x+3\right)\left(2x-1\right)\left(x-3\right)\left(4x+1\right)+44x^2\)

\(=4.\left(4x^2+4x-3\right)\left(4x^2-11x-3\right)+44x^2\)

Đặt \(4x^2+4x-3=t\)

\(\Rightarrow4.\left(2x+3\right)\left(2x-1\right)\left(x-3\right)\left(4x+1\right)+44x^2\)

\(=4.t.\left(t-15x\right)+44x^2\)

\(=4t^2-60tx+44x^2\)

\(=4.\left(t^2-15tx+11x^2\right)\)

Tự lm nốt nhé~

2) \(x^4-5x^2+4\)

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

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

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

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

1 ) ( 2x - 1 ) ( 8x + 12 ) + x²( 2x - 1 ) + ( 1 - 2x ).( 2x - 3 )

= ( 2x - 1 ) . ( 8x + 12 ) + x² ( 2x - 1 ) - ( 2x - 1 ) . ( 2x - 3 )

= ( 2x - 1 ) . ( 8x + 12 + x² - 2x + 3 )

= ( 2x - 1 ) . ( x² + 6x + 15 )

2 ) 3x ( x - y ) - 2y ( y - x ) - 4x + 4y

= 3x ( x - y ) + 2y ( x - y ) - 4. ( x - y )

= ( x - y ) ( 3x + 2y  - 4 )

Bài 1:

a) \(7x^2\left(x^2-5x+1\right)=7x^4-35x^3+7x^2\)

b) \(\left(2x-3\right)\left(x+7\right)=2x^2+11x-21\)

Bài 2:

a) \(4x^2y-8x^3y^2=4x^2y\left(1-2xy\right)\)

b) \(2x-4y-ax+2ay=x\left(2-a\right)-2y\left(2-a\right)=\left(2-a\right)\left(x-2y\right)\)

\(1,=x\left(x^2-2x+1-y^2\right)=x\left[\left(x-1\right)^2-y^2\right]=x\left(x-y-1\right)\left(x+y-1\right)\\ 2,=\left(x+y\right)^3\\ 3,=\left(2y-z\right)\left(4x+7y\right)\\ 4,=\left(x+2\right)^2\\ 5,Sửa:x\left(x-2\right)-x+2=0\\ \Leftrightarrow\left(x-2\right)\left(x-1\right)=0\Leftrightarrow\left[{}\begin{matrix}x=1\\x=2\end{matrix}\right.\)