Answer:
![y^(2)-5y=750](https://img.qammunity.org/2020/formulas/mathematics/high-school/q216r7dotme9kckm6pxb5s4zagb71mrnh3.png)
![750-y(y-5)=0](https://img.qammunity.org/2020/formulas/mathematics/high-school/ly41hh721zsii8m8293ourz7v8ij5ehlzl.png)
![(y + 25)(y -30) = 0](https://img.qammunity.org/2020/formulas/mathematics/high-school/w9nccmabvswncbg88q00f6fayyy1xqkiho.png)
Explanation:
Givens
- The area of a rectangular room is 750 square feet.
- The width of the room is 5 feet less than the length of the room.
Let's call
the width and
the length. According to the problem they are related as follows
, because the width is 5 feet less than the lenght.
We know that the area of the room is defined as
![A=w* l](https://img.qammunity.org/2020/formulas/mathematics/high-school/92axiryrnl4bbg34ppxoicnzw8vw7144wn.png)
Where
![A=750 ft^(2)](https://img.qammunity.org/2020/formulas/mathematics/high-school/9qdfuk76qt6q0gbkk7w4tsdm99yko5r2fl.png)
Replacing the given area and the expression, we have
![750=(l-5)l\\750=l^(2)-5l \\l^(2)-5l-750=0](https://img.qammunity.org/2020/formulas/mathematics/high-school/j5gv0t63zmeskgfjdxwhti3cd557uwtzhk.png)
We need to find two number which product is 750 and which difference is 5, those numbers are 30 and 25.
![l^(2)-5l-750=(l-30)(l+25)](https://img.qammunity.org/2020/formulas/mathematics/high-school/87cc2rdcsqn59ozkaroie2dneu7jbmdy7w.png)
Using the zero property, we have
![l=30\\l=-25](https://img.qammunity.org/2020/formulas/mathematics/high-school/dscc60pev4hii84avior30q7q8k034wcpg.png)
Where only the positive number makes sense to the problem because a negative length doesn't make any sense.
Therefore, the length of the room is 30 feet.
Also, the right answers are the second choice where
, the third choice and the last choice.