Explanation:
Alright so range is how far the function goes in the y direction while domain is how far the function goes in the x direction. For letter a, to find the range you would look at how high the y-values go for the graph. In this problem, the highest the graph goes is y=3 and the lowest the graph goes is y=1. This means that Range is [1,3]. The closed brackets mean the function is actually hitting the value 1 and 3 while open brackets, (x,y), mean the value does not actually hit those values. For the domain of letter a, we will look at how far the function continues in the x direction. Since the function has arrows on the end going left and right, that means that the function continues on the x-axis forever, making the domain (-∞,+∞). They are open brackets because a value can never actually be infinity. To show if it's a function, we perform the vertical line test. Basically, you put an imaginary vertical line across the whole graph and see if that line hits the function more than once. If it doesn't, like a, it's a function. If it does hit the graph twice like c, it is not a function. I hope this all makes sense.