Find the range of the graphed function.

Range is set of all y-values. To find a range of graphed function, we need to know that range starts from the minimum value of graph to maximum value. That's because the minimum value is the least value that you can get by substituting the domain and the maximum value is the largest value that you can get by substituting the domain as well.

Now we don't talk about domain here, we talk about range. See the attachment! You are supposed to focus on y-axis, plane or vertical line. See how the minimum value of function is the negative value while the maximum value is positive.

That means any ranges that don't contain the negative values are cleared out. (Hence A and C choices are wrong.)

Next, range being set of all real numbers mean that graphed functions don't have maximum value or minimum value (We can say that both max and min are infinite.)

Take a look at line graph as an example of range being set of all real numbers, or cubic function.

Answer/Conclusion

b) well because you get well

a is the correct