1. **State the problem:** Expand the expression $ab^3 c^4$ using multiplication. 2. **Recall the rules:** When variables are multiplied, write them together with multiplication symbols if needed. Exponents indicate repeated multiplication of the same base. 3. **Expand each term:** - $b^3$ means $b \times b \times b$ - $c^4$ means $c \times c \times c \times c$ 4. **Write the full expanded form:** $$a \times b \times b \times b \times c \times c \times c \times c$$ 5. **Final answer:** $$a b b b c c c c$$ This is the fully expanded multiplication form of the expression.