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:**
Jenny's deck is square with an area of $$324$$ ft². We need to find the length of one side of the deck, which is also the length of the back of Jenny's house.
2. **Formula for the area of a square:**
$$\text{Area} = \text{side}^2$$
3. **Set up the equation:**
Let $$s$$ be the length of one side of the square deck.
$$s^2 = 324$$
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 is $$18$$ ft.
**Final answer:** $$18$$ ft.