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\(x^2+9x+20\)
\(\Leftrightarrow x^2+4x+5x+20\)
\(\Leftrightarrow\left(x^2+4x\right)+\left(5x+20\right)\)
\(\Leftrightarrow x\left(x+4\right)+5\left(x+4\right)\)
\(\Leftrightarrow\left(x+4\right)\left(x+5\right)\)
\(x^2-x-20\)
\(\Leftrightarrow x^2-5x+4x-20\)
\(\Leftrightarrow\left(x^2-5x\right)+\left(4x-20\right)\)
\(\Leftrightarrow x\left(x-5\right)+4\left(x-5\right)\)
\(\Leftrightarrow\left(x-5\right)\left(x+4\right)\)
\(3x^2+x-2\)
\(\Leftrightarrow3x^2+3x-2x-2\)
\(\Leftrightarrow\left(3x^2+3x\right)-\left(2x+2\right)\)
\(\Leftrightarrow3x\left(x+1\right)-2x\left(x+1\right)\)
\(\Leftrightarrow\left(x+1\right)\left(3x-2x\right)\)
\(\)
a) 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)
b, x2 + 9x - 10
= x2 + 10x - x -10
= ( x2 - x ) +(10x - 10)
=x( x - 1) + 10 ( x - 1)
= ( x - 1)(x + 10 )
\(x^4+3x^2+36\)
\(=\left(x^2\right)^2+2.x^2.6+6^2-9x^2\)
\(=\left(x^2+6\right)^2-\left(3x\right)^2=\left(x^2-3x+6\right)\left(x^2+3x+6\right)\)
\(2x^4-3x^3-7x^2+6x+8\)
\(=2x^4+2x^3-5x^3-5x^2-2x^2-2x+8x+8\)
\(=2x^3\left(x+1\right)-5x^2\left(x+1\right)-2x\left(x+1\right)+8\left(x+1\right)\)
\(=\left(x+1\right)\left(2x^3-5x^2-2x+8\right)\)
\(=\left(x+1\right)\left[2x^2\left(x-2\right)-x\left(x-2\right)-4\left(x-2\right)\right]\)
\(=\left(x+1\right)\left(x-2\right)\left(2x^2-x-4\right)\)
Chúc bạn học tốt.
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) \(x^3-x^2-x-2\)
\(=x^3-2x^2+x^2-2x+x-2\)
\(=\left(x-2\right)\left(x^2+x+1\right)\)
a)x2+5x-6
=x2+6x-x-6
=x(x+6)-(x+6)
=(x-1)(x+6)
b)7x-6x2-2
=-6x2+3x+4x-2
=-3x(2x-1)+2(2x-1)
=(2x-1)(-3x+2)
c)x2+4x+3
=x2+3x+x+3
=x(x+3)+(x+3)
=(x+1)(x+3)
d)2x2+3x-5
=2x2+5x-2x-5
=x(2x+5)-(2x+5)
=(x-1)(2x+5)
a) 4x2 - 20x + 25 - 36y2
= (2x - 5)2 - 36y2
= (2x - 5 - 6y)(2x - 5 + 6y)
b) x3 + x2 - 2x - 8
= (x3 - 8) + (x2 - 2x)
= (x - 2)(x2 + 2x + 4) + x(x - 2)
= (x - 2)(x2 + 2x + 4 + x)
= (x - 2)(x2 + 3x + 4)
d) x4 + 6x3 + 9x2 - 16
= x2(x2 + 6x + 9) - 16
= x2(x + 3)2 - 16
= (x2 + 3x)2 - 16
= (x2 + 3x - 4)(x2 + 3x + 4)
= (x2 + 4x - x - 4)(x2 + 3x + 4)
= [x(x + 4) - (x + 4)](x2 + 3x + 4)
= (x - 1)(x + 4)(x2 + 3x + 4)
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
Cảm ơn bạn kb nha