<PRE><B>Question 1122435</B>
The distance D km between two ships A and B at time t hours is given by the formula D = 4t^2 - 36t +95. Find the minimum distance between the ships 
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1st derivative = 8t - 36
8t-36 = 0
t = 4.5 hours
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D = 4*4.5^2 - 36*4.5 + 95
D = 14 km
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Without calculus:
The closest point is the vertex of the parabola, at t = -b/2a = 36/8 = 4.5
D = 14 kms</PRE>