Question

A set of weights includes a 4 lb barbell and 6 pairs of weight plates. Each pair of plates weighs

Answer 1

Since there are no negative values for x, the range starts when y=4 at x=0. This extends infinitely in the positive direction. Therefore, the range of the function is from 4 to positive infinity. In interval notation, that is [4,∞). 

Answer 2

The range of the function is the distance from the maximum of the function to the minimum of the function. The minimum amount of pairs of plates that you can add to the bar (x) is 0, meaning you add no plates. The maximum amount of plates that you can add to the bar is 6, because this is how many plates come in one weight set. The range of the function is y values, and 0 and 6 are x values, so we must plug these values into the function to find the range values.

f(x) = 20x + 4 = 20(0) + 4 = 0 + 4 = 4

f(x) = 20x + 4 = 20(6) + 4 = 120 + 4 = 124

Therefore, the range of the function is 120 pounds, or from [4, 124].

Hope this helps!