Question 668505
Look at row 5 in Pascals triangle to see these values: 1, 4, 6, 4, 1 


These are the coefficients of each term in the form (x)^k*(y)^(n-k) where k starts at 4 and steps down to 0 (n and k are integers where n = 4)


So the expansion of (x+y)^4 is



1*(x)^4*(y)^0 + 4*(x)^3*(y)^1 + 6*(x)^2*(y)^2 + 4*(x)^1*(y)^3 + 1*(x)^0*(y)^4


1*(x^4)*(1) + 4*(x^3)*(y^1) + 6*(x^2)*(y^2) + 4*(x^1)*(y^3) + 1*(1)*(y^4)


x^4 + 4x^3y + 6x^2y^2 + 4xy^3 + y^4


Therefore the answer is: (x+y)^4 = x^4 + 4x^3y + 6x^2y^2 + 4xy^3 + y^4