1. **State the problem:** We need to find the value of the constant $a$ given that the coefficient of $x$ in the expansion of $(2 + ax)^3$ is 96.
2. **Recall the binomial expansion formula:**
$$(x + y)^n = \sum_{k=0}^n \binom{n}{k} x^{n-k} y^k$$
3. **Apply the formula to $(2 + ax)^3$:**
$$(2 + ax)^3 = \binom{3}{0} 2^3 (ax)^0 + \binom{3}{1} 2^2 (ax)^1 + \binom{3}{2} 2^1 (ax)^2 + \binom{3}{3} 2^0 (ax)^3$$
4. **Simplify each term:**
- $\binom{3}{0} 2^3 (ax)^0 = 1 \times 8 \times 1 = 8$
- $\binom{3}{1} 2^2 (ax)^1 = 3 \times 4 \times a x = 12 a x$
- $\binom{3}{2} 2^1 (ax)^2 = 3 \times 2 \times a^2 x^2 = 6 a^2 x^2$
- $\binom{3}{3} 2^0 (ax)^3 = 1 \times 1 \times a^3 x^3 = a^3 x^3$
5. **Identify the coefficient of $x$:** The coefficient of $x$ is $12 a$.
6. **Set the coefficient equal to 96 and solve for $a$:**
$$12 a = 96$$
$$a = \frac{96}{12} = 8$$
**Final answer:** The value of the constant $a$ is $8$.
Coefficient Expansion
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