<PRE><B>Question 126987</B>
The monthly sales of socks,(S on thousands of pairs) , can be calcualted by S=-t(squared)+4t+40 where t is t=0 corresponds to the first month of sales (t in months) In which months were there:
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A)When were the maximum number of socks sold? For this one I used -b/2a to find the vertex and I came up with 2 months. 
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This is correct, t = 2 is the axis of symmetry
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B) What is the maximum number of socks sold?
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To find the maximum no. of socks, substitute 2 for t and find S
S = -(2^2) + 4(2) + 40
S = -4 + 8 + 40
S = 44 thousand socks
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C)When is the number of pairs sold equal to zero? 
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Solve for t when S = 0
-t^2 + 4t + 40 = 0
This requires the quadratic formula,
Positive solution: t ~ 8.6 months
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