Simplify Expression 9B8788

1. **State the problem:** Simplify the expression $$(7s^4tu)(7st^8u)$$. 2. **Write the formula and rules:** When multiplying expressions with the same base, add the exponents: $$a^m \times a^n = a^{m+n}$$. 3. **Multiply the coefficients:** $$7 \times 7 = 49$$. 4. **Multiply the variables:** - For $s$: $$s^4 \times s^1 = s^{4+1} = s^5$$ - For $t$: $$t^1 \times t^8 = t^{1+8} = t^9$$ - For $u$: $$u^1 \times u^1 = u^{1+1} = u^2$$ 5. **Combine all parts:** $$49 s^5 t^9 u^2$$ 6. **Final answer:** The simplified expression is $$\boxed{49 s^5 t^9 u^2}$$.