By using what we know about polynomials, we will see that the missing side measures 8x - 1
How to get the perimeter of a triangle?
The perimeter of a triangle is just the sum of its 3 sides, in the image the two known sides are: 3x - 5 and x + 2, and the missing side measures p(x).
Then we will have that the perimeter is the sum of these 3 lengths:
13x - 4 = 3x - 5 + 2x + 2 + p(x)
13x - 4 = 5x - 3 + p(x)
Now we can assume that p(x) is also a linear polynomial, so:
p(x) = a*x + b
Then we have:
13x - 4 = 5x - 3 + a*x + b
This means that:
5 + a = 13
-3 + b = -4
Solving these we get:
a = 13 - 5 = 8
b = -4 + 3 = -1
This means that the missing length is:
p(x) = 8x - 1
If you want to learn more about polynomials, you can read:
https://brainly.com/question/4142886