Not a function.
It's conic section parabola. It's just a relation.
All of the numbers in the shaded part of the line have two characteristics:
==> X >= 0
==> X <= 20
This can be written as a single inequality with x in the middle, but when I type it, Brainly won't accept the characters, and says there's an error.
Here it is in words:
0 (less than or equal to) x (less than or equal to) 20 .
Answer:
second option
Step-by-step explanation:

Answer:
a = 4
Step-by-step explanation:
y = 2x + 1 ......(1)
Going through y - y1 = m(x - x1)
m is slope and it is 2
y1 = 9 and x1 = a
y - 9 = 2(x - a)
y - 9 = 2x - 2a
y = 2x - 2a + 9 ........(2)
Equating (1) and (2)
2x + 1 = 2x - 2a + 9
Collecting like terms
2x - 2x + 2a = 9 - 1
2a = 8
a = 8/2
a = 4