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a) x2 + 6x + 9 = x2 + 2 . x . 3 + 32 = (x + 3)2
b) 10x – 25 – x2 = -(-10x + 25 +x2) = -(25 – 10x + x2)
= -(52 – 2 . 5 . x – x2) = -(5 – x)2
c) 8x3 - 1/8 = (2x)3 – (1/2)3 = (2x - 1/2)[(2x)2 + 2x . 12 + (1/2)2]
= (2x - 1/2)(4x2 + x + 1/4)
d)1/25x2 – 64y2 = (1/5x)2(1/5x)2- (8y)2 = (1/5x + 8y)(1/5x - 8y)
1, x^2 +5x+4x+20
= x(x+4)+5(x+4)
= (x+5).(x+4)
2,x^2 -x -20
= x^2 -5x+4x-20
= x(x-5)+4(x-5)
=(x+4).(x-5)
3,3x^2 +3x -2x -2
= 3x(x+1)-2(x+1)
= (3x-2)(x+1)
4, 2x^2-4x-x-2
=2x(x-2)-x-2
=(2x-1)(x+2)
5,6x^2-2x+9x-3
=2x(3x-1)+3(3x-1)
=(2x+3)(3x-1)
6,3x^2 +2x+9x+6
=3x(x+3)+2(x+3)
=(3x+2)(x+3)
7,= 2(x^2-10x+3)
8,=x^4 +4^3
mk làm luôn ko chép đề nha bn
1) \(x^4+2x^3-9x^2-10x-24\)
\(=x^4+4x^3+x^2-2x^3-8x^2-2x-2x^2-8x-2\)
\(=x^2.\left(x^2+4x+1\right)-2x.\left(x^2+4x+1\right)-2.\left(x^2+4x+1\right)\)
\(=\left(x^2+4x+1\right)\left(x^2-2x-2\right)\)
2) \(6x^4+7x^3+5x^2-x-2\)
\(=6x^4-3x^3+10x^3-5x^2+10x^2-5x+4x-2\)
\(=3x^3\left(2x-1\right)+5x^2\left(2x-1\right)+5x\left(2x-1\right)+2\left(2x-1\right)\)
\(=\left(2x-1\right)\left(3x^3+5x^2+5x+2\right)\)
\(=\left(2x-1\right)\left(3x^2+2x^2+3x^2+2x+3x+2\right)\)
\(=\left(2x-1\right)\left(3x+2\right)\left(x^2+x+1\right)\)
3) \(2x^4+3x^3+2x^2-1\)
\(=2x^4+2x^3+x^3+x^2+x^2+x-x-1\)
\(=\left(x+1\right)\left(2x^3+x^2+x-1\right)\)
\(=\left(x+1\right)\left(2x-1\right)\left(x^2+x+1\right)\)
4) \(x^3-x^2-x-2\)
\(=x^3-2x^2+x^2-2x+x-2\)
\(=\left(x-2\right)\left(x^2+x+1\right)\)
\(x^2+9x+20\)
\(\Leftrightarrow x^2+4x+5x+20\)
\(\Leftrightarrow\left(x^2+4x\right)+\left(5x+20\right)\)
\(\Leftrightarrow x\left(x+4\right)+5\left(x+4\right)\)
\(\Leftrightarrow\left(x+4\right)\left(x+5\right)\)
\(x^2-x-20\)
\(\Leftrightarrow x^2-5x+4x-20\)
\(\Leftrightarrow\left(x^2-5x\right)+\left(4x-20\right)\)
\(\Leftrightarrow x\left(x-5\right)+4\left(x-5\right)\)
\(\Leftrightarrow\left(x-5\right)\left(x+4\right)\)
\(3x^2+x-2\)
\(\Leftrightarrow3x^2+3x-2x-2\)
\(\Leftrightarrow\left(3x^2+3x\right)-\left(2x+2\right)\)
\(\Leftrightarrow3x\left(x+1\right)-2x\left(x+1\right)\)
\(\Leftrightarrow\left(x+1\right)\left(3x-2x\right)\)
\(\)
\(a,3\left(x+4\right)-x^2-4x\)
\(=3\left(x+4\right)-\left(x^2+4x\right)\)
\(=3\left(x+4\right)-x\left(x+4\right)\)
\(=\left(3-x\right)\left(x+4\right)\)
\(a,3\left(x+4\right)-x^2-4x\)
\(=3\left(x+4\right)-\left(x^2+4x\right)\)
\(=3\left(x+4\right)-x\left(x+4\right)\)
\(=\left(3-x\right),\left(x+4\right)\)
1 ) x3 - 2x2 + x
= x( x2 - 2x + 1 )
= x ( x-1)2
2) 4x3 - 25x
= x ( 4x2 - 25)
= x( 2x-5) ( 2x +5)
11) \(x^2-y^2-4x+4\)
\(=\left(x^2-4x+4\right)-y^2\)
\(=\left(x-2\right)^2-y^2\)
\(=\left(x-y-2\right)\left(x+y-2\right)\)
13) \(x^4+4=x^4+4x^2+4-4x^2\)
\(=\left(x^2+2\right)^2-4x^2\)
\(=\left(x^2-2x+2\right)\left(x^2+2x+2\right)\)