Answer:
X = 5
Step-by-step explanation:
Here is what I am picturing (not to scale)
A ----------------B-----------C
We are given the information of AB (which equals 3x + 1), BC (which equals 4x - 5), and AC (which equals 8x - 9).
With reference to the line, AB + BC = AC
So,
3x + 1 + 4x - 5 = 8x - 9
7x - 4 = 8x - 9
5 = x
I can't read that language but I'll guess it says write a second degree equation then solve for n when d=10.



Answer: n² - 3n - 20 = 0
That doesn't factor so there is no integer n solution.
That means there are no polygons with 10 diagonals.

Answer:
C
Step-by-step explanation:
0.9 is the answer to this simple question