Find the slope of the graphed line

Given f(x) = 17-x^2what is the average rate of change in f(x) over the interval [1, 5]?

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Asmall business produces and sells balls. the fixed costs are $20 and each ball costs $4.32 to produce. each ball sells for $8.32. write the equations for the total cost, c, and the revenue, r, then use the graphing method to determine how many balls must be sold to break even.