Khai triển biểu thức: a) (2x+y)6 b) (x−3y)6 c) (x−1)n d) (x+2)n e) (x+y)2n f) (x−y)2n Ko sao chép timi ( sao chép = 1sao + dislike )

a) (2x+y)6 = 1*(2x)^6 + 6*(2x)^5*y + 15*(2x)^4*y^2 + 20*(2x)^3*y^3 + 15*(2x)^2*y^4 + 6*(2x)*y^5 + 1*y^6 = 64x^6 + 192x^5y + 240x^4y^2 + 160x^3y^3 + 60x^2y^4 + 12xy^5 + y^6 b) (x−3y)6 = 1*(x)^6 + 6*(x)^5*(-3y) + 15*(x)^4*(-3y)^2 + 20*(x)^3*(-3y)^3 + 15*(x)^2*(-3y)^4 + 6*(x)*(-3y)^5 + (-3y)^6 = x^6 - 18x^5y + 135x^4y^2 - 540x^3y^3 + 1215x^2y^4 - 1458xy^5 + 729y^6 c) (x−1)n = C(n,0)*(x)^n*(-1)^0 + C(n,1)*(x)^(n-1)*(-1)^1 + C(n,2)*(x)^(n-2)*(-1)^2 + ... + C(n,n-1)*(x)^1*(-1)^(n-1) + C(n,n)*(x)^0*(-1)^n = x^n - C(n,1)*x^(n-1) + C(n,2)*x^(n-2) - ... + (-1)^(n-1)*C(n,n-1)*x + (-1)^n d) (x+2)n = C(n,0)*(x)^n*(2)^0 + C(n,1)*(x)^(n-1)*(2)^1 + C(n,2)*(x)^(n-2)*(2)^2 + ... + C(n,n-1)*(x)^1*(2)^(n-1) + C(n,n)*(x)^0*(2)^n = x^n + 2C(n,1)*x^(n-1) + 4C(n,2)*x^(n-2) + ... + 2^(n-1)*C(n,n-1)*x + 2^n e) (x+y)2n = C(2n,0)*(x)^2n*(y)^0 + C(2n,1)*(x)^(2n-1)*(y)^1 + C(2n,2)*(x)^(2n-2)*(y)^2 + ... + C(2n,2n-1)*(x)^1*(y)^(2n-1) + C(2n,2n)*(x)^0*(y)^(2n) = x^(2n) + C(2n,1)*x^(2n-1)*y + C(2n,2)*x^(2n-2)*y^2 + ... + C(2n,2n-1)*x*y^(2n-1) + y^(2n) f) (x−y)2n = C(2n,0)*(x)^2n*(-y)^0 + C(2n,1)*(x)^(2n-1)*(-y)^1 + C(2n,2)*(x)^(2n-2)*(-y)^2 + ... + C(2n,2n-1)*(x)^1*(-y)^(2n-1) + C(2n,2n)*(x)^0*(-y)^(2n) = x^(2n) - C(2n,1)*x^(2n-1)*y + C(2n,2)*x^(2n-2)*y^2 - ... + (-1)^(2n-1)*C(2n,2n-1)*x*y^(2n-1) + (-y)^(2n) Trong đó, C(n,k) là tổ hợp chập k của n.