Match the range of the function f(x)=x^2x-1

Appears that you've overlooked the need to share the possible answer choices.

f(x)=x^2x-1 has a parabolic graph with vertex at (0,-1). This is also the location of the vertex. Because the coefficient of x^2 is positive, this graph opens up. Thus, the smallest possible y value here is -1. The range of this function is

[-1, infinity).

the revenue of the fitness center, y, is the product of two factors: the number of members and the fee paid by each member. there are 320 members now, but number of members goes down by 10 for each $5 increase in fees, so if x is the number of $5 price increases then members is equal to (320 - 10x). since the fee is currently $45, and the fee increases by $5 for every price bump x, the fee is given by (45 + 5x). so, revenue y is given by y = (320 - 10x)(45 + 5x).