a, (x +y)7 - x7 - y7
b, (x + y + z)5 - x5 - y5
c, a(b-c)3 + b(c-a)3 + c(a-b)3
d, a(b+c)2(b-c) + b(a+c)2(c-a) + c(a+b)2(a-b)
a, (x +y)7 - x7 - y7
b, (x + y + z)5 - x5 - y5
c, a(b-c)3 + b(c-a)3 + c(a-b)3
d, a(b+c)2(b-c) + b(a+c)2(c-a) + c(a+b)2(a-b)
c) với d) bạn tách: $b-c=[-(c-a)-(a-b)]$
Even in the games of children there are things to interest the greatest mathematician.
a, (x +y)7 - x7 - y7
b, (x + y + z)5 - x5 - y5
c, a(b-c)3 + b(c-a)3 + c(a-b)3
d, a(b+c)2(b-c) + b(a+c)2(c-a) + c(a+b)2(a-b)
a) $(x + y)^7 - x^7 - y^7 = (x + y)^7 - (x^7 + y^7) = (x + y)^7 - (x + y)(x^6 + x^5y + x^4y^2 + x^3y^3 + x^2y^4 + xy^5 + y^6) = (x + y)[(x + y)^6 - x^6 - x^5y - x^4y^2 - x^3y^3 - x^2y^4 - xy^5 - y^6)]$
b) Tương tự.
Bài viết đã được chỉnh sửa nội dung bởi Silverbullet069: 20-08-2015 - 15:06
"I am the bone of my sword,
Unknown to Death, Nor known to Life,
So as I pray, unlimited blade works."
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