Question

Can someone please explain to me how to do this?

Answer 1

The fourth coefficient is 4.

Explanation:

Pascal's Triangle in this case has 5 rows of coefficients because the highest power in (y + w)^4 is 4. 4 plus 1 is 5.

Here's the appropriate Pascal's Triangle:

1

1 1

1 2 1

1 3 3 1

1 4 6 4 1 Use this row when expanding the 4th power of (v + w).

Notice that in the given expansion, the coefficients are

1, 4, 6, 4 1

This corresponds to the last (5th) row of Pascal's Triangle (above).

So the correct coefficient to be placed in the box is 4.