1. **State the problem:** Simplify the expression $-2 \times 3x$. 2. **Formula and rules:** When multiplying a constant by a variable, multiply the constants and keep the variable as is. 3. **Intermediate work:** $$-2 \times 3x = (-2 \times 3) \times x = -6x$$ 4. **Explanation:** Multiply the numbers $-2$ and $3$ to get $-6$, then multiply by $x$ to get $-6x$. 5. **Final answer:** $$-6x$$