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Which of the functions graphed below has a removable discontinuity?

Solve for x where 0 equation: cot^2x+2cotx+1=0

The john deere company has found that revenue,in dollars, from sales of heavy-duty tractors is a function of the unit price p, in dollars, that it charges. if therevenue r is r(p)= -1/2p^2 +1900pa)how much revenue will the company generate if they sell 700 tractors? b) how many tractors does the company want to sell to maximize the revenue?