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\(8x^2-2\)
\(=2.\left(1^2-4x^2\right)\)
\(=2.\left(1-4x\right).\left(1+4x\right)\)
\(x^2-6x-y^2+9\)
\(=\left(x^2-6x+9\right)-y^2\)
\(=\left(x-3\right)^2-y^2\)
\(=\left(x-3-y\right).\left(x-3+y\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
1. \(=3x\left(2x+5\right)\)
2. \(=\left(3x-1\right)\left(3x+1\right)\)
3. \(=\left(x+3\right)^2-y^2=\left(x-y+3\right)\left(x+y+3\right)\)
1, = 3x.(2x + 5)
2. = (3x)2 - 12 = (3x - 1).(3x +1 )
3, =(x2 + 6x + 9) - y2 = (x + 3)2 - y2 =(x + y -3 ). (x - y +3)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(x^2-8y^2+6x+9\)
\(=\left(x^2+6x+9\right)-8y^2\)
\(=\left(x+3\right)^2-\left(\sqrt{8}\cdot y\right)^2\)
\(=\left(x+3+\sqrt{8}y\right)\left(x+3-\sqrt{8}y\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) Áp dụng HĐT 1 thu được ( 2 x + y ) 2 .
b) Áp dụng HĐT 3 với A = 2x + l; B = x - l thu được
[(2x +1) + (x -1)] [(2x +1) - (x -1)] rút gọn thành 3x(x + 2).
c) Ta có: 9 - 6x + x 2 - y 2 = ( 3 - x ) 2 - y 2 = (3 - x - y)(3 -x + y).
d) Ta có: -(x + 2) + 3( x 2 - 4) = -{x + 2) + 3(x + 2)(x - 2)
= (x + 2) [-1 + 3(x - 2)] = (x + 2)(3x - 7).
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(A=x^2-6x+9-9y^2\)
\(=\left(x-3\right)^2-\left(3y\right)^2\)
\(=\left(x-3-3y\right)\left(x-3+3y\right)\)
b) \(B=x^3-3x^2+3x-1+2\left(x^2-1\right)\)
\(=\left(x-1\right)^3+\left(2x+2\right)\left(x-1\right)\)
\(=\left(x-1\right)\left[\left(x-1\right)^2+2x+2\right]\)
\(=\left(x-1\right).\left(x^2+3\right)\)
a, \(A=\left(x-3\right)^2-9y^2=\left(x-3-3y\right)\left(x-3+3y\right)\)
b, \(B=\left(x-1\right)^3+2\left(x-1\right)\left(x+1\right)=\left(x-1\right)\left[\left(x-1\right)^2+2\left(x+1\right)\right]\)
\(=\left(x-1\right)\left(x^2-2x+1+2x+2\right)=\left(x-1\right)\left(x^2+3\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) Kết quả 2x(2x – 3). b) Kết quả xy( x 2 – 2xy + 5).
c) Kết quả 2x(x + 1)(x + 4). d) Kết quả 2 5 ( y − 1 ) ( x + y ) .
a/ \(\left(x^2-x+2\right)^2+\left(x-2\right)^2=\left(x^2-x+2\right)^2-x^2+x^2+\left(x-2\right)^2\)
\(=\left(x^2-2x+2\right)\left(x^2+2\right)+2x^2-4x+4\)
\(=\left(x^2-2x+2\right)\left(x^2+2\right)+2\left(x^2-2x+2\right)\)
\(=\left(x^2-2x+2\right)\left(x^2+4\right)\)
b/ \(6x^5+15x^4+20x^3+15x^2+6x+1\)
\(=6x^5+6x^4+2x^3+9x^4+9x^3+3x^2+9x^3+9x^2+3x+3x^2+3x+1\)
\(=2x^3\left(3x^2+3x+1\right)+3x^2\left(3x^2+3x+1\right)+3x\left(3x^2+3x+1\right)+3x^2+3x+1\)
\(=\left(3x^2+3x+1\right)\left(2x^3+3x^2+3x+1\right)\)
\(=\left(3x^2+3x+1\right)\left(x^3+\left(x+1\right)^3\right)\)
\(=\left(3x^2+3x+1\right)\left(2x+1\right)\left(x^2-\left(x+1\right)x+\left(x+1\right)^2\right)\)
\(=\left(3x^2+3x+1\right)\left(3x+1\right)\left(x^2+x+1\right)\)