The total area of a rectangular-shaped garden is:
![x^3+7x^2+7x-15](https://img.qammunity.org/2023/formulas/mathematics/college/64coiwugxrji85zg06y22489r19rkwe7yu.png)
We have that the area of a rectangle is
![A=L\cdot W](https://img.qammunity.org/2023/formulas/mathematics/college/hezcw344p4b25gymdlhot9itkb3i1yoax2.png)
We have the total area given by the expression above. We also have the length, given by:
![L=x+3](https://img.qammunity.org/2023/formulas/mathematics/college/pgi86qb8oedkhxsph6lnh1kjn1rt5p80xj.png)
Then
![x^3+7x^2_{}+7x-15=(x+3)\cdot W](https://img.qammunity.org/2023/formulas/mathematics/college/5xh1303olf8acq1k7tr8st9opwkwgoqwzc.png)
![W=(x^3+7x^2+7x-15)/(x+3)](https://img.qammunity.org/2023/formulas/mathematics/college/z13svow12za7z9bnv7uqw2vj7ear4uh3i5.png)
We need to solve this polynomial division:
Therefore, the width is
![x^2+4x-5](https://img.qammunity.org/2023/formulas/mathematics/college/u92hmiy4uhoynvakwqlcktcbbq55zfktti.png)
The perimeter is the sum of all the sides of the rectangle:
![2W+2L\rightarrow2\cdot(x^2+4x-5)+2\cdot(x+3)=(2x^2+8x-10)+2x+6](https://img.qammunity.org/2023/formulas/mathematics/college/24ne7be8guuza9wpvsm4pg0uxtwloqx43e.png)
![2x^2+10x-4](https://img.qammunity.org/2023/formulas/mathematics/college/7gbznsqgf7z5f6wf0ya96cqdhd5mwwp72o.png)
So, the perimeter is 2x^2+10x-4.
The width is x^2+4x-5.