Find the coordinates of a point on the parabola y = x2 + 7x + 2 which is closest to the straight line y = 3x – 3.



Given equation of the parabola is y = x2 + 7x + 2 and straight line is y = 3x - 3 or 3x - y - 3 = 0


Equation of parabola y = x2 + 7x + 2 …… (1)


Let us assume the point on parabola which is closest to the line be (x, y)


We know that distance between the point (x0, y0) and the line ax + by + c = 0 is



Now we find the distance between the line and point on parabola



From(1)





Let us assume S be the function of x




For maxima and minima




2x + 4 = 0


2x = - 4


x = - 2


Now differentiating again




At x = - 2



We get the minimum distance at x = - 2


Let’s find the value of y at this x value


y = ( - 2)2 + 7( - 2) + 2


y = 4 - 14 + 2


y = - 8


The point ( - 2, - 8) is the nearest point on the parabola to the line y = 3x - 3.


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