It looks like you have to do distance formula. It's basically this:
D =
(ignore the A, i dont know how to get rid of it sorry)
I would then plug in the points of A(1,7) and B(10,3).
D = 
Then I would get the square root of 4^2 + 9^2
= square root of 16 + 81
= square root of 97
So the length of AB would be the square root of 97
Answer: The missing length is 16/3
Step-by-step explanation:
First, you have to find the proportional value between the two lengths on the first figure and the two lengths on the second figure.
The first figure’s lengths are 8 and 9, so the shorter length is 8/9 of the longer length.
Now apply the same proportional value to the second figure.
6 * 8/9 = 48/9
48/9 = 16/3
F(4z) = 3 * (4z)^2 - 6
= 48z^2 - 6