Differentiate the square of the distance

In summary, the conversation discussed finding the point on the graph of f(x)=√x that is closest to the value (4,0) by differentiating the square of the distance from a point on the graph to the given value. The equation D(x)=((x-4)^2+x) was used to represent the square of the distance, and by finding the minimum of D'(x), the point (7/2, √(7/2)) was determined to be the closest point on the graph to the given value.
  • #1
chapsticks
38
0

Homework Statement




Find the point on the graph of f(x)=√x that is closest to the value (4,0).

(differentiate the square of the distance from a point (x,√x) on the graph of f to the point (4,0).)

Homework Equations




f(x)=√x

The Attempt at a Solution


Square of distance from (4,0)
D(x)= ((x-4)^2+x)
For minimum, D'(x)=0
2(x-4)+1=0
x=7/2
 
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  • #2
chapsticks said:

Homework Statement




Find the point on the graph of f(x)=√x that is closest to the value (4,0).

(differentiate the square of the distance from a point (x,√x) on the graph of f to the point (4,0).)

Homework Equations




f(x)=√x

The Attempt at a Solution


Square of distance from (4,0)
D(x)= ((x-4)^2+x)
D(x) doesn't represent the distance - it's the square of the distance. As it turns out, though, mininimizing the distance is equivalent to minimizing the square of the distance.
chapsticks said:
For minimum, D'(x)=0
2(x-4)+1=0
x=7/2
This is the correct value of x, but you haven't answered the question, which is to find the point on the graph of f(x)=√x that is closest to the [STRIKE]value[/STRIKE] point (4,0).
 
  • #3
I don't get it?
 
  • #4
Mark44 told you you have the right x value. Now what point is that on the graph?
 
  • #5
Is it (7/2,(√7/2))?
 
  • #6
It depends on what you mean by (√7/2).

This is [itex]\sqrt{7}/2[/itex].
 
  • #7
Oh I mean √7/√2
 
  • #8
Which is the same as √(7/2). So, yes, (7/2, √(7/2)) is the right point on the graph of f(x) = √x.
 
  • #9
Yay thanks
 

Related to Differentiate the square of the distance

1. What is the square of the distance?

The square of the distance is a mathematical concept that involves squaring the distance between two points. It is calculated by multiplying the distance by itself.

2. How do you differentiate the square of the distance?

To differentiate the square of the distance, you need to use the power rule in calculus. First, square the distance and then differentiate it as you would with any other function. This will give you the derivative of the square of the distance.

3. What is the purpose of differentiating the square of the distance?

Differentiating the square of the distance can help in solving problems related to motion, such as finding the velocity or acceleration of an object. It is also useful in calculating the slope of a line or the curvature of a curve.

4. Is the square of the distance the same as the distance squared?

No, the square of the distance and the distance squared are not the same. The square of the distance refers to the distance between two points being multiplied by itself, while the distance squared refers to the distance being multiplied by itself twice.

5. Can the square of the distance be negative?

No, the square of the distance cannot be negative. Distance is a positive quantity and when squared, it will always result in a positive value. This is because the square of any number is always positive, regardless of the sign of the original number.

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