On the parabola y = x 2 , the point least distant from the straight line y = 2 x − 1 is
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Let the point on the parabola y = x 2 be ( x , x 2 ) .
Let the point on the straight line y = 2 x − 1 be ( x , 2 x − 1 ) .
Using the distance formula, we get the distance between the two points as:
( x − x ) 2 + ( x 2 − 2 x + 1 ) 2
= ( x 2 − 2 x + 1 ) 2
= x 2 − 2 x + 1
To get the minimum distance, we use the concept of minima-maxima.
that is, d x d ( x 2 − 2 x + 1 ) = 0
⟹ 2 x − 2 = 0
⟹ x = 1
Thus the point on the parabola is ( 1 , 1 ) .
Your solution assumes that the "closest points" must lie on a vertical line. This need not be true for any 2 random curves. It just so happens that these curves touch, which is why your solution appears to work.
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If any point coincides, then it is the closest.
Checking if there is a real number solution for the two equations x 2 − 2 x + 1 = 0 ( x − 1 ) 2 = 0 When x is 1, y is 1. Point (1,1) is satisfying both equations.