Which of the following integrals are improper? (Select all that

Monincbh

Monincbh

Answered question

2021-12-01

Which of the following integrals are improper?
4515x1 dx  
х0112х1 dx  
sin(x)1+3x2 dx  
13ln(x1) dx 

Answer & Explanation

John Twitchell

John Twitchell

Beginner2021-12-02Added 19 answers

A definite integral with one or both infinite bounds is referred to as an improper integral, as is an integrand that approaches infinity at one or more places in the integration range.
1)4515x1
1x=ln|x|
4515x1=15ln|5x1|45=15{ln|24|ln|19|}
Integral is not improper.
2)0112x1
plugging x=12,the integral appto aches0, and x=12 is within the range of integration [0,1].
So this is an improper integration.
3)sinx1+3x2 dx 
It is an improper integral.
4)13ln(x1) dx 
at x=1, the integral becomes undefined and x=1 is within the range of integration.
so it is an improper integration.
Answer that option (2),(3) and (4) are examples of improper integration.

star233

star233

Skilled2023-05-14Added 403 answers

Answer:
a) The integral 4515x1dx is not improper.
b) The integral x0112x1dx is improper.
c) The integral sin(x)1+3x2dx is improper.
d) The integral 13ln(x1)dx is not improper.
Explanation:
a) To determine if the integral 4515x1dx is improper, we need to check if the interval of integration includes any points of discontinuity or if the integrand becomes unbounded within that interval. In this case, the integrand 15x1 is continuous and defined for all x within the interval [4,5]. Therefore, the integral is not improper.
b) The integral x0112x1dx is improper because the integrand 12x1 becomes unbounded when x=12, which falls within the interval of integration [0,1]. To evaluate this improper integral, we split it into two parts:
x0112x1dx=lima12(x0a12x1dx)+limb12+(xb112x1dx)
c) The integral sin(x)1+3x2dx is improper because the interval of integration extends to infinity. To evaluate this improper integral, we can use the symmetry property of the sine function:
sin(x)1+3x2dx=20sin(x)1+3x2dx
d) The integral 13ln(x1)dx is not improper because both the integrand ln(x1) and the interval of integration [1,3] are well-defined and finite.
alenahelenash

alenahelenash

Expert2023-05-14Added 556 answers

Step 1:
a) 4515x1dx is not improper because the limits of integration, 4 and 5, are finite.
Step 2:
b) x0112x1dx is improper because the integrand becomes infinite at x=12.
Step 3:
c) sin(x)1+3x2dx is improper because the limits of integration are infinite.
Step 4:
d) 13ln(x1)dx is not improper because the limits of integration, 1 and 3, are finite.
karton

karton

Expert2023-05-14Added 613 answers

To determine which of the following integrals are improper, let's analyze each integral one by one.
1) 4515x1dx
This integral is a definite integral over a finite interval, from x=4 to x=5. Since the interval is finite, this integral is not improper.
2) x0112x1dx
Similar to the previous integral, this is also a definite integral over a finite interval, from x=0 to x=1. Thus, this integral is not improper.
3) sin(x)1+3x2dx
This integral is an example of an improper integral because the integration limits extend to infinity. To solve this integral, we can split it into two separate integrals:
sin(x)1+3x2dx=0sin(x)1+3x2dx+0sin(x)1+3x2dx
Each of these individual integrals is improper, and we need to evaluate them separately.
4) 13ln(x1)dx
This integral is a definite integral over a finite interval, from x=1 to x=3. Therefore, it is not an improper integral.
In summary:
- The integrals in parts 1) and 2) are not improper integrals.
- The integral in part 3) is an improper integral.
- The integral in part 4) is not an improper integral.

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