Example 1
Determine the area of a rectangle when its side lengths are [[$ 2x +1 $]] and [[$ 3x + 4 $]].
![Example 1.](https://peda.net/qis/2022-2023/mathematics/maths-grade-9/oipjp/1pkp/esimerkki-1/7:file/photo/fb3af1f3cc77d924e6ccf9e1fdb4dd8fc5dcb7d5/16_esimerkki1a_taitto.png)
The area of the rectangle is the sum of the areas of the four smaller rectangles:
[[$ A = 6x^2+8x+3x+4=6x^2+11x+4 $]]On the other hand, the area can also be calculated as the product of the lengths of the rectangle's sides.
![Example 1.](https://peda.net/qis/2022-2023/mathematics/maths-grade-9/oipjp/1pkp/esimerkki-1/72:file/photo/e0a5cdbf8131389d488c21aaa8d5dcb84d6ae4a1/16_esimerkki1b_taitto.png)
Answer: The area of the rectangle is [[$ 6x^2+11x+4 $]].