Area summation problem under a curve

In summary, the formula given in the homework statement involves a sum of square roots in the numerator and ##n^{3/2}## in the denominator. However, the correct form is ##\sum_k f(c_k) \Delta x## with ##c_k=k \cdot \Delta x\, , \,f(c_k)=\sqrt{c_k}## and ## \Delta x=\frac{1}{n}##. The formula provided by the student is missing the substitution of ## \Delta x=\frac{1}{n}##, which explains the presence of ##n^{3/2}## in the denominator.
  • #1
Karol
1,380
22

Homework Statement


Snap2.jpg

Why, in:
$$\frac{\sqrt{1}+\sqrt{2}+...+\sqrt{n}}{n^{3/2}}$$
There is ##~n^{3/2}## in the denominator?

Homework Equations


Snap2.jpg


The Attempt at a Solution


it should be:
$$S_n=\sqrt{c_1}\Delta x+\sqrt{c_2}\Delta x+...=\Delta x\cdot \sqrt{\Delta x}+\Delta x\cdot \sqrt{2\Delta x}+...=\sqrt{\Delta x}\cdot \Delta x(\sqrt{1}+\sqrt{2}+...+\sqrt{n})$$
 
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  • #2
Karol said:

Homework Statement


View attachment 135725
Why, in:
$$\frac{\sqrt{1}+\sqrt{2}+...+\sqrt{n}}{n^{3/2}}$$
There is ##~n^{3/2}## in the denominator?

Homework Equations


View attachment 135842

The Attempt at a Solution


it should be:
$$S_n=\sqrt{c_1}\Delta x+\sqrt{c_2}\Delta x+...=\Delta x\cdot \sqrt{\Delta x}+\Delta x\cdot \sqrt{2\Delta x}+...=\sqrt{\Delta x}\cdot \Delta x(\sqrt{1}+\sqrt{2}+...+\sqrt{n})$$
It should be ##\sum_k f(c_k) \Delta x##. Now ##c_k=k \cdot \Delta x\, , \,f(c_k)=\sqrt{c_k}## and ## \Delta x=\frac{1}{n}##. You simply stopped too soon before substituting ## \Delta x=\frac{1}{n}##.
 
  • #3
Thank you fresh_42
 

Related to Area summation problem under a curve

What is the "area summation problem under a curve"?

The area summation problem under a curve is a mathematical concept where the area under a curve on a graph is calculated by dividing the curve into small rectangles and summing their areas. This is done to approximate the total area under the curve, which can be a complex shape.

Why is the area summation problem under a curve important?

The area under a curve represents the total value or quantity in a given situation. By solving the area summation problem, we can accurately estimate this value and make informed decisions in various fields, such as economics, physics, and engineering.

What is the process for solving the area summation problem under a curve?

The process involves dividing the curve into small rectangles, calculating their respective areas, and then summing them to obtain an approximation of the total area under the curve. This can be done using numerical methods, such as the trapezoidal rule or Simpson's rule, or by using the fundamental theorem of calculus.

Are there any limitations to the area summation problem under a curve?

Yes, there are some limitations to this method. One limitation is that it can only provide an approximation of the total area under the curve, not an exact value. Additionally, the accuracy of the approximation depends on the number of rectangles used and the complexity of the curve. As the number of rectangles increases, the accuracy improves, but it also increases the computational time.

What are some real-world applications of the area summation problem under a curve?

The area summation problem is used in various fields, such as physics to calculate work and energy, economics to estimate total revenue and profit, and environmental science to estimate the total carbon footprint. It is also used in data analysis and machine learning to calculate the area under a ROC curve, which is a measure of a model's performance.

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