When I use the product rule to find the derivative of xe^(-x) I get xe^(-x) + e^(-x) but the correct answer is y'=(1-x)e^(-x) which is e^(-x) - xe^(-x) why am I getting a plus when the answer is a minus?
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Hey kingsolomonsgrave. Recall that d/dx e^(-x) = -e^(-x).
oh! thanks
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