Area Under Graph: Calculate (1+2^x) from 0 to 30

  • Context: Undergrad 
  • Thread starter Thread starter whatdofisheat
  • Start date Start date
  • Tags Tags
    Area
Click For Summary

Discussion Overview

The discussion centers on calculating the area under the graph of the function (1 + 2^x) from 0 to 30. Participants explore the mathematical approach to finding this area through integration, while also addressing the concept of area under curves in relation to positive and negative values of functions.

Discussion Character

  • Mathematical reasoning
  • Conceptual clarification

Main Points Raised

  • One participant asks how to calculate the area under the graph of (1 + 2^x) from 0 to 30 and seeks the answer.
  • Another participant provides the integral of the function, suggesting the area can be calculated as \(\left( {x + \frac{{2^x }}{{\log 2}}} \right)_0^{30} = 30 + \frac{{2^{30} - 1}}{{\log 2}}\).
  • A participant explains that the integral represents the area bounded by the graph of the function, the x-axis, and vertical lines at the limits of integration, cautioning that the term "area under the curve" can be misleading when the function is negative.
  • Another participant agrees with the previous point but questions its relevance to the current function, noting that (1 + 2^x) is positive for all real x, thus confirming that the integral indeed represents the area under the curve as intended by the original poster.
  • A hint is provided regarding the integral of exponential functions, suggesting a formula for integration.

Areas of Agreement / Disagreement

Participants generally agree on the method of calculating the area under the curve for the function (1 + 2^x) and acknowledge its positivity over the specified interval. However, there is a discussion about the general concept of area under curves, particularly regarding functions that may take negative values, which remains a point of clarification rather than a disagreement.

Contextual Notes

The discussion includes nuances about the interpretation of integrals and the conditions under which they represent area, particularly in relation to positive and negative function values. There are also references to specific mathematical steps that may require further elaboration.

whatdofisheat
Messages
24
Reaction score
0
to take the area under a graph of
(1+2^x) from 0 to 30 how can you do this and what is the answer
 
Physics news on Phys.org
[tex]\int\limits_0^{30} {\left( {1 + 2^x } \right)dx} = \left( {x + \frac{{2^x }}{{\log 2}}} \right)_0^{30} = 30 + \frac{{2^{30} - 1}}{{\log 2}}[/tex]

Questions like these belong here :)
 
Last edited:
If you have a function f(x), it's integral from a to b is the area bounded by the graph of the function, the x-axis and the lines y=a, y=b.

The term "area under the curve" can lead to confusion, because in the intervals where the function is negative, the integral actually gives the negative of the area not under but above the curve.

exemple: the integral of sin(x) between 0 and 2pi is 0 because there is a "mountain" over the x-axis, followed by a "valley" (under the x-axis). The total area under the mountain is A, and the area over the valley is A also, but since f(x) is negative there, this area is substracted while calculating the integral...

[tex]\int_0^{2\pi}\sin(x)dx = \int_0^{\pi}\sin(x)dx+\int_{\pi}^{2\pi}\sin(x)dx = A+(-A)=0[/tex]
 
quasar987 said:
The term "area under the curve" can lead to confusion, because in the intervals where the function is negative, the integral actually gives the negative of the area not under but above the curve.
True indeed, but how does that apply here? 1+2x > 0 for all real x, so [itex]\int\limits_0^{30} {\left( {1 + 2x} \right)dx}[/itex] is (represents) indeed, as asked by the OP, the area under the curve y=1+2x (additionally bounded by y=0, x=0, and x=30).
whatdofisheat said:
to take the area under a graph of
(1+2^x) from 0 to 30 how can you do this and what is the answer
:redface: Hint:
[tex]\forall a > 0,\;\int {a^x dx} = \frac{{a^x }}{{\log a}} + C[/tex]
 
Last edited:
bomba923, when you delete a message do you have a "Physically remove" button below "Delete" and "Do Not Delete"? If so, clicking on that will not leave the "debris" behind that just using "Delete" does!

(I tried sending this as a private message but your box is full. Please go to your User CP and delete at least some of the private messages you have been getting.)
 
HallsofIvy said:
bomba923, when you delete a message do you have a "Physically remove" button below "Delete" and "Do Not Delete"? If so, clicking on that will not leave the "debris" behind that just using "Delete" does!
I don't have a "physically remove" button anywhere! :frown:

*Can you add it to my account?
(*e.g., somewhat like adding avatar privileges to PF contributors' accounts, but in this case, adding a button/option around the "delete post" button...something like that, so I can physically my remove posts :redface:)
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 5 ·
Replies
5
Views
4K
  • · Replies 24 ·
Replies
24
Views
4K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K