Question

How do you expand `(y^4+2x)^7`?

Answer 1

`1(y^4)^7 + 7(y^4)^6(2x) + 21(y^4)^5(2x)^2 + 35(y^4)^4(2x)^3 + 35(y^4)^3(2x)^4 + 21(y^4)^2(2x)^5 + 7(y^4)(2x)^6 + 1(2x)^7`

Explanation:

1
1,1
1,2,1
1,3,3,1
1,4,6,4,1
1,5,10,10,5,1
1,6,15,20,15,6,1

`1,7,21,35,35,21,7,1`

`sum_{k = 0}^n frac{7!}{k! (7-k)!} (y^4)^(7 - k)(2x)^k`