1. **State the problem:** Expand the expression $ (x+9)(x+8) $. 2. **Formula used:** Use the distributive property (FOIL method) for binomials: $$ (a+b)(c+d) = ac + ad + bc + bd $$ 3. **Apply the formula:** $$ (x+9)(x+8) = x \cdot x + x \cdot 8 + 9 \cdot x + 9 \cdot 8 $$ 4. **Calculate each term:** $$ x^2 + 8x + 9x + 72 $$ 5. **Combine like terms:** $$ x^2 + (8x + 9x) + 72 = x^2 + 17x + 72 $$ 6. **Final answer:** $$ x^2 + 17x + 72 $$ This is the expanded form of $ (x+9)(x+8) $.