Reverse diferentiation problem

  • Thread starter cd246
  • Start date
  • Tags
    Reverse
In summary: I understand now.In summary, the correct way to integrate (x^2+3x-1)/x^4 is to first rewrite it as x^-2+3x^-3-x^-4. Then, using "backwards differentiation," we add 1 to the exponent and divide by the new exponent, giving us -x^-1+(3/2)x^-2-(1/3)x^-3+C as the final answer. Remember to be careful with signs and exponents when integrating.
  • #1
cd246
30
0

Homework Statement


(x^2+3x-1)/x^4 the answer is,(-x^-1)-(3/2)(x^-2)+(1/3)(x^-3)+C

Homework Equations


Just reverse diferentiation

The Attempt at a Solution


=x^2+3x-1+x^-4
=(x^3)/(3)+(3x^2)/(2)-x+(1/3)(x^-3+C)
(1/3)(x^3)+(3/2)(x^2)-x+(1/3)(x^-3)+C
I know i got the answer but somehow it is backwards(exponents mostly). What am I doing wrong?
 
Physics news on Phys.org
  • #2
cd246 said:

Homework Statement


(x^2+3x-1)/x^4 the answer is,(-x^-1)-(3/2)(x^-2)+(1/3)(x^-3)+C

Homework Equations


Just reverse diferentiation

The Attempt at a Solution


=x^2+3x-1+x^-4
=(x^3)/(3)+(3x^2)/(2)-x+(1/3)(x^-3+C)
(1/3)(x^3)+(3/2)(x^2)-x+(1/3)(x^-3)+C
I know i got the answer but somehow it is backwards(exponents mostly). What am I doing wrong?
Look at your signs on the exponents before you intergrate and be careful, that should take care of it.
 
  • #3
Remember in "backwards differentiation":
i) Exponent +1
ii) divide with the new exponent.

[tex](x^2+3x-1)/x^4 = x^{-2} + 3x^{-3} - x^{-4} [/tex]

the first term:
[tex]x^{-2} \rightarrow (x^{-2+1})/(-2+1) = -x^{-1}[/tex]
etc.
 
  • #4
cd246 said:

Homework Statement


(x^2+3x-1)/x^4 the answer is,(-x^-1)-(3/2)(x^-2)+(1/3)(x^-3)+C


Homework Equations


Just reverse diferentiation


The Attempt at a Solution


=x^2+3x-1+x^-4
=(x^3)/(3)+(3x^2)/(2)-x+(1/3)(x^-3+C)
(1/3)(x^3)+(3/2)(x^2)-x+(1/3)(x^-3)+C
I know i got the answer but somehow it is backwards(exponents mostly). What am I doing wrong?

Perhaps it would help if you told us what the question is!

Are you trying to integrate (x^2+ 3x-1)/x^4?

You then write "= x^2+ 3x-1+ x^-4" which is not at all the same thing: you are adding x^-4 rather than dividing by x^4.

(x^2+ 3x- 1)/x^4= (x^2/x^4)+ 3(x/x^4)- 1/x^4= x^-2+ 3x^-3- x^-4.
Now integrate.
 
  • #5
malawi_glenn said:
Remember in "backwards differentiation":
i) Exponent +1
ii) divide with the new exponent.

[tex](x^2+3x-1)/x^4 = x^{-2} + 3x^{-3} - x^{-4} [/tex]

the first term:
[tex]x^{-2} \rightarrow (x^{-2+1})/(-2+1) = -x^{-1}[/tex]
etc.

Now I know what I did wrong now, I just put x^-4 on top instead of subtracting the lower from the upper which I should have done. Thanks glenn
 

Related to Reverse diferentiation problem

1. What is reverse differentiation problem?

Reverse differentiation problem is a mathematical concept that involves finding the original function when only the derivative of the function is known. It is also known as the inverse differentiation problem.

2. Why is reverse differentiation problem important?

Reverse differentiation problem is important in many areas of science and engineering, such as physics, economics, and control theory. It allows us to determine the original function from its derivative, which is useful in understanding the behavior of systems and making predictions.

3. How is reverse differentiation problem solved?

Reverse differentiation problem can be solved using different techniques, such as integration, inverse trigonometric functions, and logarithmic functions. It requires a good understanding of mathematical principles and techniques.

4. What are the applications of reverse differentiation problem?

Reverse differentiation problem has many applications in real-world problems, such as in finding the original displacement or velocity from the acceleration of an object, determining the original function from its rate of change, and calculating the original demand or supply curve from the marginal cost or revenue.

5. Are there any challenges in solving reverse differentiation problem?

Solving reverse differentiation problem can be challenging because there is no unique solution in many cases. It is also important to consider the domain and range of the original function and make sure that the solution is valid for all values of the independent variable.

Similar threads

  • Calculus and Beyond Homework Help
Replies
10
Views
535
  • Calculus and Beyond Homework Help
Replies
25
Views
473
  • Calculus and Beyond Homework Help
Replies
5
Views
998
  • Calculus and Beyond Homework Help
Replies
6
Views
1K
  • Calculus and Beyond Homework Help
Replies
16
Views
2K
  • Calculus and Beyond Homework Help
Replies
5
Views
589
  • Calculus and Beyond Homework Help
Replies
4
Views
1K
  • Calculus and Beyond Homework Help
Replies
8
Views
911
  • Calculus and Beyond Homework Help
Replies
4
Views
936
  • Calculus and Beyond Homework Help
Replies
3
Views
990
Back
Top