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6.  Find the point on the curve y2 = 4x which is nearest to the point (2, 1).

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Let (h,k) be any point on the curve y2=4xSo, (h,k) satisfies the equation y2=4xi.e k2=4hh=k24Now, distance between (h,k) and (2,1) isD=h-22+(k-1)2    Distance formula between two pointsD=k24-22+(k-1)2D2=k24-22+(k-1)2Differentaite it w.r.t.k., we het2DdDdk=2k24-2×ddkk24-2+2(k-1)×ddk(k-1)2DdDdk=2k24-2k2+2(k-1)DdDdk=k24-2k2+(k-1)dDdk=1Dk24-2k2+(k-1)For the required point to be nearest to the point (2,1) distance D should be minimum i.e dDdk=0So,1Dk24-2k2+(k-1)=0k24-2k2+(k-1)=0k-1=0 or k24-2k2=0k=1 or k24-2=0k=1 or k=22So, When k=1, then h=14When k=22,then h=2224=2So, Required points are 14,1 or 2,22

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