Help Me, please.

( x + y)^4

We can use the 4th row of Pascal's Triangle for the coefficients.....the first row is "row 0"

1   4      6      4     1

So  we have

1x^4  +   4x^3y   +  6x^2y^2  + 4xy^3  + 1y^4

Note, Manuel.....the sum of the exponents in each term  = 4  ......

Thanks