Binomial Cube D078A6
1. **State the problem:** Expand the expression $$(4a - b)^3$$.
2. **Formula used:** The cube of a binomial $$(x - y)^3$$ expands as $$x^3 - 3x^2y + 3xy^2 - y^3$$.
3. **Identify terms:** Here, $$x = 4a$$ and $$y = b$$.
4. **Apply the formula:**
$$
(4a - b)^3 = (4a)^3 - 3(4a)^2(b) + 3(4a)(b)^2 - b^3
$$
5. **Calculate each term:**
- $$(4a)^3 = 64a^3$$
- $$3(4a)^2(b) = 3 imes 16a^2 imes b = 48a^2b$$
- $$3(4a)(b)^2 = 3 imes 4a imes b^2 = 12ab^2$$
- $$b^3 = b^3$$
6. **Combine with signs:**
$$
64a^3 - 48a^2b + 12ab^2 - b^3
$$
7. **Final answer:**
$$(4a - b)^3 = 64a^3 - 48a^2b + 12ab^2 - b^3$$