a function is where you input something and get out another thing
generally you are talking about one-to-one functions where for every input you get exactly one output
x is input and y is input
basicaly, x never repeats
2 ways to find a function
1. if on a graph, then it must pass the vertical line test whre if you draw a vertical line ANYWHERE on the graph, then it must pass through the graph of the equation no more than one times
2. if on a set then make sure that x doesn't repeat with a different y so if you had (2,3) and (2,4) then that is not a function
A is a function since passes vertical line test
B is a function since x doesn't repeat
C is NOT a function since x=3 has a y value of 5 and -2
D is NOT a function since you have the points (2,2) and (2,6)
so select A and B
basically just lok at the first number of each ordered pair (x,y) and make sure the first number never repeats with a different second number (x,y) and (x,z) is not function if z is not equal to y
so
1 is a function since the numbers never repat
2 is NOT a function since we have the points (2,3) and (2,5)
3 is NOT a function since we have th points (4,2) nd (4,8) and the points (6,3) and (6,6)
4 is NOT a function since we have the points (6,8) and (6,4)
so only first is function
ANSWERS
so the functions are
A and B for first quetsion
#1 fors econd
