Question: Jenny wants to build a square deck that is attached to the back of her house. Because the deck will be square, each side of it will be equal in length to the back of Jenny’s house. When Jenny’s deck is finished, its area will be 324 ft². What is the length of the back of Jenny’s house?
1. **State the problem:** We need to find the length of one side of a square deck given its area is $$324$$ ft².
2. **Formula:** The area $$A$$ of a square with side length $$s$$ is given by $$A = s^2$$.
3. **Apply the formula:** We know $$A = 324$$, so:
$$s^2 = 324$$
4. **Solve for $$s$$:** Take the square root of both sides:
$$s = \sqrt{324}$$
5. **Calculate the square root:**
$$s = 18$$
6. **Interpretation:** The length of the back of Jenny’s house, which is the side length of the deck, is $$18$$ ft.
**Final answer:** $$18$$ ft.