Question

What is the coefficient of the 2nd term of the following expression when written in standard form:

〖(7+4x)〗^3

Answer 1

336

Explanation:

Given the expansion:
`(7+4x)^3`

`(7+4x)^3\\\\=(7+4x)^2*(7+4x)\\\\=(7+4x)(16x^2+56x+49)\\\\=7(16x^2+56x+49)+4x(16x^2+56x+49)\\\\=112x^2+392x+343+64x^3+224x^2+196x\\\\=64x^3+112x^2+224x^2+392x+196x+343\\\\=64x^3+336x^2+588x+343`

Therefore, the coefficient of the second term is 336.