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A student Sumit is running on a playground along the curve given by y=x2+7y = x^2 + 7. Another student Amit standing at a point with co-ordinates (3,7)(3, 7) on the playground wants to hit Sumit by paper ball, when Sumit is nearest to him.

Based on the above information answer the following.

If D is the distance between Sumit and Amit, then the value of xx for which D is minimum, is :

Solution

✅ Correct Option: 3

Minimize D2=(x−3)2+x4D^2 = (x-3)^2 + x^4. d(D2)dx=2(x−3)+4x3=0⇒4x3+2x−6=0⇒2x3+x−3=0\frac{d(D^2)}{dx} = 2(x-3) + 4x^3 = 0 \Rightarrow 4x^3 + 2x - 6 = 0 \Rightarrow 2x^3 + x - 3 = 0. x=1x = 1 is a root: 2+1−3=02+1-3 = 0. Hence x=1x = 1.

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