Is This Integral Calculation Correct?

  • Thread starter Thread starter lemon26
  • Start date Start date
Click For Summary
The discussion revolves around the integration of the function (5x^2 + √x - 4/x^2) dx. The user has attempted the integration and arrived at the expression 5x^3 / 3 + 2x^3/2 / 3 + 4 / x + c but is unsure about its correctness and tidiness. There is confusion regarding the interpretation of the integral due to the lack of parentheses, leading to multiple possible interpretations of the function to be integrated. The user also seeks clarification on integration rules and the concept of integration by parts. Overall, the thread highlights the need for precise notation in mathematical expressions to avoid misinterpretation.
lemon26
Messages
1
Reaction score
0
Hi, can anyone help please as I'm getting tied up in knots...

Homework Statement



Integrate (5x^2 + √x - 4/x^2) dx

Homework Equations



I think this is differentiating by parts...

The Attempt at a Solution



So far I've got to: 5x^3 / 3 + 2x^3/2 / 3 + 4 / x +c

I can't think how I can make it any tidier so any tips would be really appreciated!
 
Physics news on Phys.org
Two questions for you:

(1) What is:
\int( f(x) + g(x)) dx
(2) What is:
\int x^k dx
 
Question (3): What is 'differentiating by parts'?
 
lemon26 said:
Hi, can anyone help please as I'm getting tied up in knots...

Homework Statement



Integrate (5x^2 + √x - 4/x^2) dx

Homework Equations



I think this is differentiating by parts...

The Attempt at a Solution



So far I've got to: 5x^3 / 3 + 2x^3/2 / 3 + 4 / x +c

I can't think how I can make it any tidier so any tips would be really appreciated!

Because you do not use parentheses, I cannot figure out whether you mean
(1) \; \int \left(5 x^2 + \sqrt{x} - \frac{4}{x^2} \right) \, dx \leftarrow \text{ what you wrote}
or
(2) \; \int \left( 5 x^2 + \sqrt{x - \frac{4}{x^2}} \right) \, dx
or
(3) \;\int \left(5 x^2 - \frac{ \sqrt{x-4}}{x^2} \right)\, dx
or
(4) \;\int \left(5 x^2 - \sqrt{ \frac{x-4}{x^2} } \right)\, dx
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

Similar threads

  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
5
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
Replies
11
Views
2K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
Replies
4
Views
2K