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21 tháng 9 2017
a )
b)
c) x^5 - x^4 - 1
= x^5 - x^3 - x² - x^4 + x² + x + x^3 - x - 1
= x²( x^3 - x - 1 ) - x( x^3 - x - 1 ) + ( x^3 - x - 1 )
= ( x² - x + 1)( x^3 - x - 1 )
d)
2 tháng 10 2019
a, x^2 + 2xy + y^2 - x - y - 12
= (x^2 + 2xy + y^2) - (x + y) - 16 + 4
= (x + y)^2 - 4^2 - (x + y - 4)
= (x + y - 4)(x + y + 4) - (x + y - 4)
= (x + y - 4)(x + y + 4 - 1)
= (x + y - 4)(x + y + 3)
b, x^6 + 27
= (x^2)^3 + 3^3
= (x^2 + 3)[(x^2)^2 - 3x^2 + 3^2]
= (x^2 + 3)(x^4 - 3x^2 + 9)
c, x^7 + x^5 + 1
=x^7 - x^6 + x^5 - x^3 + x^2 + x^6 - x^5 + x^4 - x^2 + x + x^5 - x^4 + x^3 - x + 1
= (x^2 + x + 1)(x^5 - x^4 + x^3 - x+1)
PT
2
TP
11 tháng 7 2017
Ta có:
\(x^7+x^5+1=x.x.x.x.x.x.x+x.x.x.x.x+1\)
\(=x.x.x.x.x\left(x.x+1\right)\)
Kết quả như vậy phải không. Mình chưa học mới xem sơ thôi. Nếu sai bạn đừng trách.
S
3
3 tháng 6 2018
a.
\(x^7+x^2+1=\left(x^7-x\right)+\left(x^2+x+1\right)\)
\(=x\left(x^6-1\right)+\left(x^2+x+1\right)=x\left(x^3-1\right)\left(x^3+1\right)+\left(x^2+x+1\right)\)
\(=x\left(x-1\right)\left(x^2+x+1\right)\left(x^3+1\right)+\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left[x\left(x-1\right)\left(x^3+1\right)\right]\)
\(=\left(x^2+x+1\right)\left[\left(x^2-x\right)\left(x^3+1\right)\right]\)
\(=\left(x^2+x+1\right)\left(x^5+x^2-x^4-x\right)\)
b.
\(x^8+x+1=\left(x^8-x^5\right)+\left(x^5-x^2\right)+\left(x^2+x+1\right)\)
\(=x^5\left(x^3-1\right)+x^2\left(x^3-1\right)+\left(x^2+x+1\right)\)
\(=x^5\left(x-1\right)\left(x^2+x+1\right)+x^2\left(x-1\right)\left(x^2+x+1\right)+\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left[x^5\left(x-1\right)+x^2\left(x-1\right)+1\right]\)
\(=\left(x^2+x+1\right)\left[\left(x-1\right)x^2\left(x^3+1\right)+1\right]\)
\(=\left(x^2+x+1\right)\left[\left(x^3-x^2\right)\left(x^3+1\right)+1\right]\)
\(=\left(x^2+x+1\right)\left(x^6-x^5+x^3-x^2+1\right)\)
3 tháng 6 2018
a) \(x^7+x^2+1=x^7+x^6+x^5-x^5+x^4-x^4+x^3-x^3+2x^2\)\(-x^2+x-x+1\)
\(=\left(x^7+x^6+x^5\right)-\left(x^6+x^5+x^4\right)+\left(x^4+x^3+x^2\right)\)\(-\left(x^3+x^2+x\right)+\left(x^2+x+1\right)\)
\(=x^5\left(x^2+x+1\right)-x^4\left(x^2+x+1\right)+x^2\left(x^2+x+1\right)\)\(-x\left(x^2+x+1\right)+\left(x^2+x+1\right)\)
\(=\left(x^5-x^4+x^2-x+1\right)\left(x^2+x+1\right)\)
b) \(x^8+x+1=x^8-x^2+\left(x^2+x+1\right)=x^2\left(x^6-1\right)\)\(+\left(x^2+x+1\right)\)
\(=x^2\left(x^3+1\right)\left(x^3-1\right)+\left(x^2+x+1\right)\)
\(=x^2\left(x^3+1\right)\left(x-1\right)\left(x^2+x+1\right)\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left[x^2\left(x^3+1\right)\left(x-1\right)+1\right]\)
DX
0
\(x^7+x^2+1\)
\(=x^7+x^6+x^5+x^4+x^3+x^2+x+1\)
\(=x^5\left(x^2+x+1\right)-x^4\left(x^2+x+1\right)+x^2\left(x^2+x+1\right)-x\left(x^2+x+1\right)+\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^5-x^4+x^2-x+1\right)\)
a) \(x^7+x^2+1=\left(x^7-x\right)+\left(x^2+x+1\right)\)
\(=x\left(x^6-1\right)+\left(x^2+x+1\right)=x\left(x^3-1\right)\left(x^3+1\right)+\left(x^2+x+1\right)\)
\(=x\left(x-1\right)\left(x^2+x+1\right)\left(x^3+1\right)+\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left[x\left(x-1\right)\left(x^3+1\right)+1\right]\)
\(=\left(x^2+x+1\right)\left(x^5-x^4+x^2-x+1\right)\)
b) \(x^7+x^5+1=\left(x^7+x^6+x^5\right)-\left(x^6-1\right)\)
\(=x^5\left(x^2+x+1\right)-\left(x^3-1\right)\left(x^3+1\right)\)
\(=x^5\left(x^2+x+1\right)-\left(x-1\right)\left(x^2+x+1\right)\left(x^3+1\right)\)
\(=\left(x^2+x+1\right)\left[x^5-\left(x-1\right)\left(x^3+1\right)\right]\)
\(=\left(x^2+x+1\right)\left(x^5-x^4+x^3-x+1\right)\)