1. **Problem Statement:** We need to write the formula for the volume of a solid obtained by rotating the curve $$ y = f(x), \quad a \leq x \leq b $$ about the x-axis. 2. **Formula Used:** The volume $V$ of the solid formed by revolving the curve $y=f(x)$ from $x=a$ to $x=b$ about the x-axis is given by the disk method: $$ V = \pi \int_a^b [f(x)]^2 \, dx $$ 3. **Explanation:** - The curve $y=f(x)$ is rotated around the x-axis, creating circular cross-sections (disks) perpendicular to the x-axis. - Each disk has radius $r = f(x)$ and area $A = \pi r^2 = \pi [f(x)]^2$. - Integrating these areas from $a$ to $b$ sums up the volume of all disks, giving the total volume. 4. **Summary:** The volume formula for the solid of revolution about the x-axis is: $$ \boxed{V = \pi \int_a^b [f(x)]^2 \, dx} $$ This formula applies to any continuous function $f(x)$ on $[a,b]$ where $f(x) \geq 0$ to represent the radius of the disks.