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a) x4 + 1997x2 + 1996x +1997
= x4 + 1997x2 + 1997x - x +1997
=(x4-x) + (1997x2 +1997x+1997)
=x(x3-1) + 1997(x2+x+1)
=x(x-1)(x2+x+1) + 1997(x2+x+1)
=(x2+x+1)(x2-x) + 1997(x2+x+1)
=(x2+x+1)(x2-x+1997)
b) x2 -x -2001.2002
=x2 - x -20022 +2002
=(x2-20022)-(x-2002)
=(x-2002)(x+2002) - (x-2002)
=(x-2002)(x+2002+1)
=(x-2002)(x+2003)
c)x8 + 98x4 +1
= (x8+2x4+1) + 96x4
= (x4+1)2 + 96x4
=[(x4+1)2 + 2.(x4+1).8 + 64x4 ]+[32x4 - 16x2(x4+1)]
=(x4+1+8x2)-16x2(-2x2+x4+1)
=(x4+8x2+1)2- 16x2(x2-1)2
=(x4 + 8x2 +1)2- [4x(x2-1)]2
=(x4+8x2+1)2 - (4x3-4x)2
=(x4-4x3+8x2+4x+1)(x4+4x3+8x2-4x+1)
bn chép lại đề nha
\(=x^4-x+1997\left(x^2+x+1\right)\)
\(=x\left(x-1\right)\left(x^2+x+1\right)+1997\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^2-x+1997\right)\)
xong nha. chúc bn hc tốt
a) \(x^5-2x^4+3x^3-4x^2+2\)
\(=x^5-x^4-x^4+x^3+2x^3-2x^2-2x^2+2\)
\(=x^4\left(x-1\right)-x^3\left(x-1\right)+2x^2\left(x-1\right)-2\left(x-1\right)\left(x+1\right)\)
\(=\left(x-1\right)\left(x^4-x^3+2x^2-2x-2\right)\)
b) \(x^4+1997x^2+1996x+1997\)
\(=\left(x^4+x^2+1\right)+1996\left(x^2+x+1\right)\)
\(=\left(x^2-x+1\right)\left(x^2+x+1\right)+1996\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^2-x+1997\right)\)
c) \(x^8+x^4+1\)
\(=x^8+2x^4+1-x^4\)
\(=\left(x^4+1\right)-x^4\)
\(=\left(x^4-x^2+1\right)\left(x^4+x^2+1\right)\)
\(=\left(x^4-x^2+1\right)\left(x^2-x+1\right)\left(x^2+x+1\right)\)
c) \(x^5+x+1\)
\(=x^5-x^2+x^2+x+1\)
\(=x^2\left(x^3-1\right)+\left(x^2+x+1\right)\)
\(=x^2\left(x-1\right)\left(x^2+x+1\right)+\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^3-x^2+1\right)\)
Pt vô nghiệm
=> dùng hệ số bất định hay phân tích có nhân tử là (x2+x+1)
a) Ta có : x2 - 4x + 3
= x2 - x - 3x + 3
= x(x - 1) - (3x - 3)
= x(x - 1) - 3(x - 1)
= (x - 1) (x - 3)
a) \(x^2-4x+3\)
\(=x^2-x-3x+3\)
\(=x\left(x-1\right)-3\left(x-1\right)\)
\(=\left(x-1\right)\left(x-3\right)\)
b) \(x^2+5x+4\)
\(=x^2+x+4x+4\)
\(=x\left(x+1\right)+4\left(x+1\right)\)
\(=\left(x+1\right)\left(x+4\right)\)
c) \(x^2-x-6\)
\(=x^2-3x+2x-6\)
\(=x\left(x-3\right)+2\left(x-3\right)\)
\(=\left(x+2\right)\left(x-3\right)\)
d) \(x^4+1997x^2+1996x+1997\)
\(=x^4+x^2+1996x^2+1996x+1996+1\)
\(=\left(x^4+x^2+1\right)+\left(1996x^2+1996x+1996\right)\)
\(=\left(x^2+x+1\right)\left(x^2-x+1\right)+1996\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^2-x+1997\right)\)
e) \(x^2-2001\cdot2002\)( hình như sai sai)
a) \(x^4+1997x^2+1996x+1997\)
\(=\left(x^4-x\right)+\left(1997x^2+1997x+1997\right)\)
\(=x\left(x^3-1\right)+1997\left(x^2+x+1\right)\)
\(=x\left(x-1\right)\left(x^2+x+1\right)+1997\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left[x\left(x-1\right)+1997\right]\)
\(=\left(x^2+x+1\right)\left(x^2-x+1997\right)\)
b) \(x^2-x-2015.2016\)
\(=x^2-2016x+2015x-2015.2016\)
\(=\left(x^2-2016x\right)+\left(2015x-2015.2016\right)\)
\(=x\left(x-2016\right)+2015\left(x-2016\right)\)
\(=\left(x-2016\right)\left(x+2015\right)\)