Answer:
![A = 12n^4-15n^3-3n^2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/au53hbq8u1xcl91lm6d7kagt3soyg7al1x.png)
Explanation:
The dimensions of a rectangle are length and breadth/width
Here we are given height . Assuming it to be one of the side of the rectangle , we will do the further calculation
Hence one side is
side 1 =
![3n^2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/8tjhtwe48hgrb33mwefse0xw4xxxlomvxb.png)
And the other side is
Side 2 =
![4n^2-5n-1](https://img.qammunity.org/2020/formulas/mathematics/middle-school/kjdd99w6dc9bh5fmb2kg7hdt5s7x3w08mz.png)
The area of rectangle = side 1 x side 2
![A=3n^2 * (4n^2-5n-1)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/tapyi71pem5c8kvv26b0x04kzfem9vhgdu.png)
![A=3n^2 * 4n^2-3n^2 * 5n-3n^2 * 1](https://img.qammunity.org/2020/formulas/mathematics/middle-school/vpykcajaccisn9jkctq7ap66r3shxsvubq.png)
![A=3 * 4 * n^2 * n^2- 3 * 5 * n^2 * n - 3n^2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/llq3onjlgk1akhwn5qgby8cmuyewwi80bt.png)
![A = 12n^4-15n^3-3n^2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/au53hbq8u1xcl91lm6d7kagt3soyg7al1x.png)
Hence area can be given as expression
![A = 12n^4-15n^3-3n^2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/au53hbq8u1xcl91lm6d7kagt3soyg7al1x.png)