Lots of points.
1 function or not

explain when you get the answer

2
function or not

explain when you have the answer

3
function or not

explain when you have the answer

1.  Not a function.

2. This is a function.

3. This is a function.

Step-by-step explanation:

1. 13 maps on to 4 and -4 so not a function.

2 and 3 - these both pass the vertical line test so they are functions.

the graph top, left is y = 4x

step-by-step explanation:

∆abc has the points a(1, 7), b(-2, 2), and c(4, 2) as its vertices. formed with the point d(1, 2) as its third vertex, then ∆abd is triangle.