Edwin
Use the formula for a specific term of a binomial expansion:
(a + b)n = nC(r - 1) * (a)(n - (r - 1)) * (b)(r - 1)
We have:, with:
Term number, or
(a + b)n = nC(r - 1) * (a)(n - (r - 1)) * (b)(r - 1)
4th term of: (4x + 5y)6: 6C(4 - 1) * (4x)(6 - (4 - 1)) * (5y)(4 - 1)
4th term of (4x + 5y)6: 6C3 * (4x)3 * (5y)3
4th term of (4x + 5y)6: 20 * 64x3 * 125y3
4th term of: