Answer:
![4x^2 + 36x + 80](https://img.qammunity.org/2021/formulas/mathematics/college/uoqczoo9rlrk5hrpwz5ud2mlfd1w84gcnb.png)
Explanation:
Area of the photograph with the mat = area of the photograph + area of the mat
Area of the photograph = length * width = 10*8 = 80 in²
Area of the mat:
Decompose the mat frame into 4 rectangles and 4 squares (these are the corners of x*x dimensions)
The 4 rectangles = 2(8*x) + 2(10*x) = 16x + 20x = 36x
The 4 squares (the corners) = 4(x*x) = 4x²
The area of the photograph with the mat = 80 + 36x + 4x²
Rearrange in standard form:
The expression for the area would be:
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![4x^2 + 36x + 80](https://img.qammunity.org/2021/formulas/mathematics/college/uoqczoo9rlrk5hrpwz5ud2mlfd1w84gcnb.png)