Find the point on the curve y2 = 4x which is nearest to the point (2, –8).


Given Curve is y2 = 4x …… (1)


Let us assume the point on the curve which is nearest to the point (2, - 8) be (x, y)


The (x, y) satisfies the relation(1)


Let us find the distance(S) between the points (x, y) and (2, - 8)


We know that distance between two points (x1,y1) and (x2,y2) is .





Squaring on both sides we get,


S2 = x2 + y2 - 4x + 16y + 68


From (1)




We know that distance is an positive number so, for a minimum distance S, S2 will also be minimum


Let us S2 as the function of y.


For maxima and minima,






y3 - 64 = 0



On solving we get



Now differentiating again




At y = 4




We get minimum distance at y = 4


Let find the value of x at these y values



x = 4


The nearest point to the point (2, - 8) on the curve is (4,4).


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