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1, 9x2 - 9xy- 4y2
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\(9x^2-4y^2\)
\(=\left(3x\right)^2-\left(2y\right)^2\)
\(=\left(3x-2y\right)\left(3x+2y\right)\)
a) \(9x^2-16\)
\(=\left(3x\right)^2-4^2\)
\(=\left(3x-4\right)\left(3x+4\right)\)
b) \(x^2+4xy+4y^2-3x-6y\)
\(=\left(x^2+4xy+4y^2\right)-\left(3x+6y\right)\)
\(=\left[x^2+2\cdot x\cdot2y+\left(2y\right)^2\right]-3\left(x+2y\right)\)
\(=\left(x+2y\right)^2-3\left(x+2y\right)\)
\(=\left(x+2y\right)\left(x+2y-3\right)\)
#\(Toru\)
Ta có: \(1+6x-6x^2-x^3\)
\(=-x^3-6x^2+6x+1\)
\(=\left(-x^3+1\right)-6x\left(x-1\right)\)
\(=-\left(x-1\right)\left(x^2+x+1\right)-6x\cdot\left(x-1\right)\)
\(=\left(x-1\right)\left(-x^2-x-1-6x\right)\)
\(=-\left(x-1\right)\left(x^2+7x+1\right)\)
\(\dfrac{1}{2}x^3+4\)
\(=\dfrac{1}{2}\left(x^3+8\right)\)
\(=\dfrac{1}{2}\left(x^3+2^3\right)\)
\(=\dfrac{1}{2}\left(x+2\right)\left(x^2-2\cdot x+2^2\right)\)
\(=\dfrac{1}{2}\left(x+2\right)\left(x^2-2x+4\right)\)
1)
\(y^2-4y+4-x^2\\ =\left(y-2\right)^2-x^2\\ =\left(y-2-x\right)\left(y-2+x\right)\)
2)
\(8x^3-12x^2+6x-2\\ =2\left(4x^3-6x^2+3x-1\right)\\ =2\left(4x^3-4x^2-2x^2+2x+x-1\right)\\ =2\left(4x^2\left(x-1\right)-2x\left(x-1\right)+\left(x-1\right)\right)\\ =2\left(x-1\right)\left(4x^2-2x+1\right)\)
1) \(y^2-4y+4-x^2\)
\(=\left(y^2-4y+4\right)-x^2\)
\(=\left(y-2\right)^2-x^2\)
\(=\left(y-2-x\right)\left(y-2+x\right)\)
2) \(8x^3-12x^2+6x-1\)
\(=\left(2x\right)^3-3\cdot\left(2x\right)^2\cdot1+3\cdot2x\cdot1^2-1^3\)
\(=\left(2x-1\right)^3\)
\(=\left(2x-1\right)\left(2x-1\right)\left(2x-1\right)\)
1: \(x^2-3x+2=\left(x-1\right)\left(x-2\right)\)
2: \(x^2-x-6=\left(x-3\right)\left(x+2\right)\)
3: \(x^2+7x+12=\left(x+3\right)\left(x+4\right)\)
1) \(x^2-3x+2=\left(x^2-x\right)-\left(2x-2\right)=x\left(x-1\right)-2\left(x-1\right)=\left(x-1\right)\left(x-2\right)\)
2) \(x^2-x-6=\left(x^2-3x\right)+\left(2x-6\right)=x\left(x-3\right)+2\left(x-2\right)=\left(x-2\right)\left(x-3\right)\)
3) \(x^2+7x+12=\left(x^2+3x\right)+\left(4x+12\right)=x\left(x+3\right)+4\left(x+3\right)=\left(x+3\right)\left(x+4\right)\)
1: \(x^2-3x+2=\left(x-1\right)\left(x-2\right)\)
2: \(x^2-x-6=\left(x-3\right)\left(x+2\right)\)
3: \(x^2+7x+12=\left(x+3\right)\left(x+4\right)\)
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)
9x2 - 9xy - 4y2
=( 9x2 - 4y2 ) - 9xy
= ( 3x - 2y ) ( 3x + 2y ) - 9xy