Math Problem Statement

Find the point on the graph of the function that is closest to the given point: f(x) = √(x - 7), (10, 0).

Solution

To find the point on the graph of f(x)=x7f(x) = \sqrt{x - 7} that is closest to the point (10,0)(10, 0), we can proceed with the following steps:

  1. Define the Distance Function:
    The distance dd between a point on the curve (x,f(x))(x, f(x)) and the point (10,0)(10, 0) is given by: d=(x10)2+(x70)2=(x10)2+(x7)d = \sqrt{(x - 10)^2 + \left( \sqrt{x - 7} - 0 \right)^2} = \sqrt{(x - 10)^2 + (x - 7)}

  2. Simplify the Distance Function:
    To make it easier to work with, we'll minimize the square of the distance instead of dd itself (since the square root is a monotonic function, this won't change the minimum point): d2=(x10)2+(x7)d^2 = (x - 10)^2 + (x - 7) Expanding this expression: d2=(x10)2+x7=x220x+100+x7=x219x+93d^2 = (x - 10)^2 + x - 7 = x^2 - 20x + 100 + x - 7 = x^2 - 19x + 93

  3. Find the Minimum of d2d^2:
    To minimize d2d^2, we take the derivative with respect to xx and set it to zero: ddx(d2)=2x19=0\frac{d}{dx}(d^2) = 2x - 19 = 0 Solving for xx: x=192=9.5x = \frac{19}{2} = 9.5

  4. Find yy Value on the Curve:
    Now, substitute x=9.5x = 9.5 into f(x)f(x) to find yy: f(9.5)=9.57=2.5f(9.5) = \sqrt{9.5 - 7} = \sqrt{2.5}

So, the point on the graph closest to (10,0)(10, 0) is: (x,y)=(9.5,2.5)(x, y) = \left( 9.5, \sqrt{2.5} \right)

Would you like a more detailed explanation, or have any questions?


Related Questions:

  1. How do you find the minimum distance from a point to a line instead of a curve?
  2. Why does minimizing d2d^2 yield the same result as minimizing dd?
  3. Can the method used here be applied to other functions, like polynomial functions?
  4. How would the process change if the point were further away, say at (20,0)(20, 0)?
  5. How can we use calculus to verify that our minimum distance is indeed the closest point?

Tip:

In optimization problems involving distance, minimizing the square of the distance often simplifies calculations by removing the square root, while still preserving the location of the minimum.

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Math Problem Analysis

Mathematical Concepts

Distance Minimization
Derivative
Square Root Function

Formulas

Distance formula d = √((x - x1)^2 + (y - y1)^2)
Derivative of d^2 with respect to x

Theorems

Optimization using derivatives

Suitable Grade Level

Grades 11-12