Question

Find the 5th term in the expansion of (x – 3y)^8

Answer 1

5670 x^4 y^4

Explanation:

Using Pascal's triangle, we know that the 5th term will have:

70x^4 y^4.

Now we simply need to determine the coefficient for this. Plug in 1 for x as x in (x-3y)^8 has a coefficient of one, and plug in -3 for y for the same reason. The result is:

70(1^4)(-3^4) = 81 * 70 = 5670.

As a result, the 5th term is 5670(x^4)(y^4).