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\(a^{10}+a^5+1\)
\(a^{10}+a^5+1=\left(a^2+a+1\right)\left(a^8-a^7+a^5-a^4+a^3-a+1\right)\)
a10 + a5 + 1
= a10 - a9 + a7 - a6 + a5 - a3 + a2 + a9 - a8 + a6 - a5 + a4 - a3 + a + a8 - a7 + a5 - a4 + a2 - a + 1
nhóm 7 hạng tử ta đc :
= a2(a8 - a7 + a5 - a4 + a3 - a + 1) + a(a8 - a7 + a5 - a4 + a3 - a + 1) + (a8 - a7 + a5 - a4 + a3 - a + 1)
= (a2 + a + 1)(a8 - a7 + a5 - a4 + a3 - a + 1)
= x.(x3 - 1).(x6 + x3 + 1) + x2.(x3 - 1) + (x2 + x + 1)
= (x2 + x + 1). [x.(x -1).(x6 + x3 + 1) + x2 + 1 ]
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Cho mình viết a thành x nhé !
x^10 + x^5 + 1
= x^10 + x^9 - x^9 + x^8 - x^8 + x^7 - x^7 + x^6 - x^6 + x^5 + x^5 - x^5 + x^4 - x^4 + x^3 - x^3 + x^2 - x^2 + x - x + 1
= (x^10 + x^9 + x^8) - (x^9 + x^8 + x^7) + (x^7 + x^6 + x^5) - (x^6 + x^5 + x^4) + (x^5 + x^4 + x^3) - (x^3 + x^2 + x) + (x^2 + x + 1)
= x^8 (x^2 + x + 1) - x^7 (x^2 + x + 1) + x^5 (x^2 + x + 1) - x^4 (x^2 + x + 1) + x^3 (x^2 + x + 1) - x (x^2 + x + 1) + (x^2 + x + 1)
= (x^2 + x + 1) (x^8 - x^7 + x^5 - x^4 + x^3 - x + 1)
a, x10+x9+x8-x9-x8-x7+x7+x6+x5-x6-x5-x4+x5+x4+x3-x3-x2-x+x2+x+1 = x8(x2+x+1)-x7(x2+x+1)+x5(x2+x+1)-x4(x2+x+1)+x3(x2+x+1)-x(x2+x+1)+(x2+x+1) =(x8-x7+x5-x4+x3-x+1)
b,x8+x7+x6-x7-x6-x5+x5+x4+x3-x3-x2-x+x2+x+1 =x6( x2+x+1)-x5(x2+x+1)+x3(x2+x+1)-x(x2+x+1)+(x2+x+1) = (x2+x+1)(x6-x5+x3-x+1)
a)Ta có: x10+x5+1=x10+x7-x7+x6-x6+x5+1
=(x10-x7) - (x6-1) + (x7+x6+x5)
=x7(x3-1) - ((x3)2-1) + (x2+x+1)
=x7(x-1)(x2+x+1) - (x3-1)(x3+1) + x5(x2+x+1)
=x7(x-1)(x2+x+1) - (x-1)(x2+x+1)(x3+1) + x5(x2+x+1)
=(x2+x+1)(x7(x+1)-(x+1)(x3+1)+x5)
=(x2+x+1)(x8-x7+x5-x4+x3-x+1)
x^4+x^2+1 = (x^4+2x^2+1)-x^2 = (x^2+1)^2-x^2 = (x^2-x+1).(x^2+x+1)
k mk nha
x5-x4-1=x5-x3-x2-x4+x2+x+x3-x-1
=x2.(x3-x-1)-x.(x3-x-1)+(x3-x-1)
=(x3-x-1)(x2-x+1)
x^4+x^2+1 = (x^4+2x^2+1)-x^2 = (x^2+1)^2-x^2 = (x^2-x+1).(x^2+x+1)
k mk nha
\(a^{10}+a^5+1\)
\(=\left(a^{10}-a\right)+\left(a^5-a^2\right)+\left(a^2+a+1\right)\)
\(=a\left(a^3-1\right).\left(a^6+a^3+1\right)+a^2\left(a^3-1\right)+\left(a^2+a+1\right)\)
\(=a\left(a-1\right)\left(a^2+a+1\right)+\left(a^6+a^3+1\right)+a^2\left(a-1\right)\left(a^2+a+1\right)\)+ (a²+a+1)
Đến đây rùi thì tự làm tiếp nha
\(a^{10}+a^5+1\)
\(=\left(a^{10}+a^9+a^8\right)-\left(a^9+a^8+a^7\right)+\left(a^7+a^6+a^5\right)-\left(a^6+a^5+a^4\right)+\left(a^5+a^4+a^3\right)-\left(a^3+a^2+a\right)+\left(a^2+a+1\right)\)\(=\left(a^2+a+1\right)\left(a^8-a^7+a^5-a^4+a^3-a+1\right)\)