The market for sweet potatoes consists of 1,000 identical firms. Each firm has a short-run total cost curve of STC = 100 + 100 q + 100q^2, and a short-run marginal cost curve of SMC=100+200q, where q is output. What is the equation of the firm's average variable cost curve?

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I know that STC=TVC+TFC --> ATC=AVC+ATC and from equation STC=100+100q+100q^2 so ATC=100/q+100+100q. Then what should I do?