Solving $int sqrt{x}left(1+sqrt{x}right)^3mathrm{d}x $
$begingroup$
$$ int sqrt{x}left(1+sqrt{x}right)^3dx $$
I tried to solve this by using substitution. However, I could not reach the answer.
I tried to replace $1+sqrt{x} = u$ and
$sqrt{x} = u$
But still did not get the answer.I don't want to open parenthesis and solve integral in that way.
calculus integration
$endgroup$
|
show 1 more comment
$begingroup$
$$ int sqrt{x}left(1+sqrt{x}right)^3dx $$
I tried to solve this by using substitution. However, I could not reach the answer.
I tried to replace $1+sqrt{x} = u$ and
$sqrt{x} = u$
But still did not get the answer.I don't want to open parenthesis and solve integral in that way.
calculus integration
$endgroup$
$begingroup$
Do you mean $$int sqrt{x} cdot left(1+sqrt{x}right)^3;?$$
$endgroup$
– Chinnapparaj R
Dec 17 '18 at 15:35
$begingroup$
Yes,thanks for correcting
$endgroup$
– Arif Rustamov
Dec 17 '18 at 15:40
3
$begingroup$
Mutliply out the cube to get four terms. Multiply through by the square root. Then you have an easy sum of powers.
$endgroup$
– Ethan Bolker
Dec 17 '18 at 15:40
3
$begingroup$
Why exactly would you not want to expand the integrand?
$endgroup$
– KM101
Dec 17 '18 at 15:42
1
$begingroup$
If you do a substitution you will still have parentheses that need opening: you may get three rather than four terms, but at the cost of the substitution, and for an indefinite integral the cost of re-substitution
$endgroup$
– Henry
Dec 17 '18 at 15:55
|
show 1 more comment
$begingroup$
$$ int sqrt{x}left(1+sqrt{x}right)^3dx $$
I tried to solve this by using substitution. However, I could not reach the answer.
I tried to replace $1+sqrt{x} = u$ and
$sqrt{x} = u$
But still did not get the answer.I don't want to open parenthesis and solve integral in that way.
calculus integration
$endgroup$
$$ int sqrt{x}left(1+sqrt{x}right)^3dx $$
I tried to solve this by using substitution. However, I could not reach the answer.
I tried to replace $1+sqrt{x} = u$ and
$sqrt{x} = u$
But still did not get the answer.I don't want to open parenthesis and solve integral in that way.
calculus integration
calculus integration
edited Dec 17 '18 at 15:54
Rebellos
15.3k31250
15.3k31250
asked Dec 17 '18 at 15:33
Arif RustamovArif Rustamov
387
387
$begingroup$
Do you mean $$int sqrt{x} cdot left(1+sqrt{x}right)^3;?$$
$endgroup$
– Chinnapparaj R
Dec 17 '18 at 15:35
$begingroup$
Yes,thanks for correcting
$endgroup$
– Arif Rustamov
Dec 17 '18 at 15:40
3
$begingroup$
Mutliply out the cube to get four terms. Multiply through by the square root. Then you have an easy sum of powers.
$endgroup$
– Ethan Bolker
Dec 17 '18 at 15:40
3
$begingroup$
Why exactly would you not want to expand the integrand?
$endgroup$
– KM101
Dec 17 '18 at 15:42
1
$begingroup$
If you do a substitution you will still have parentheses that need opening: you may get three rather than four terms, but at the cost of the substitution, and for an indefinite integral the cost of re-substitution
$endgroup$
– Henry
Dec 17 '18 at 15:55
|
show 1 more comment
$begingroup$
Do you mean $$int sqrt{x} cdot left(1+sqrt{x}right)^3;?$$
$endgroup$
– Chinnapparaj R
Dec 17 '18 at 15:35
$begingroup$
Yes,thanks for correcting
$endgroup$
– Arif Rustamov
Dec 17 '18 at 15:40
3
$begingroup$
Mutliply out the cube to get four terms. Multiply through by the square root. Then you have an easy sum of powers.
$endgroup$
– Ethan Bolker
Dec 17 '18 at 15:40
3
$begingroup$
Why exactly would you not want to expand the integrand?
$endgroup$
– KM101
Dec 17 '18 at 15:42
1
$begingroup$
If you do a substitution you will still have parentheses that need opening: you may get three rather than four terms, but at the cost of the substitution, and for an indefinite integral the cost of re-substitution
$endgroup$
– Henry
Dec 17 '18 at 15:55
$begingroup$
Do you mean $$int sqrt{x} cdot left(1+sqrt{x}right)^3;?$$
$endgroup$
– Chinnapparaj R
Dec 17 '18 at 15:35
$begingroup$
Do you mean $$int sqrt{x} cdot left(1+sqrt{x}right)^3;?$$
$endgroup$
– Chinnapparaj R
Dec 17 '18 at 15:35
$begingroup$
Yes,thanks for correcting
$endgroup$
– Arif Rustamov
Dec 17 '18 at 15:40
$begingroup$
Yes,thanks for correcting
$endgroup$
– Arif Rustamov
Dec 17 '18 at 15:40
3
3
$begingroup$
Mutliply out the cube to get four terms. Multiply through by the square root. Then you have an easy sum of powers.
$endgroup$
– Ethan Bolker
Dec 17 '18 at 15:40
$begingroup$
Mutliply out the cube to get four terms. Multiply through by the square root. Then you have an easy sum of powers.
$endgroup$
– Ethan Bolker
Dec 17 '18 at 15:40
3
3
$begingroup$
Why exactly would you not want to expand the integrand?
$endgroup$
– KM101
Dec 17 '18 at 15:42
$begingroup$
Why exactly would you not want to expand the integrand?
$endgroup$
– KM101
Dec 17 '18 at 15:42
1
1
$begingroup$
If you do a substitution you will still have parentheses that need opening: you may get three rather than four terms, but at the cost of the substitution, and for an indefinite integral the cost of re-substitution
$endgroup$
– Henry
Dec 17 '18 at 15:55
$begingroup$
If you do a substitution you will still have parentheses that need opening: you may get three rather than four terms, but at the cost of the substitution, and for an indefinite integral the cost of re-substitution
$endgroup$
– Henry
Dec 17 '18 at 15:55
|
show 1 more comment
2 Answers
2
active
oldest
votes
$begingroup$
Let $u = sqrt{x}+1 implies mathrm{d}x = 2sqrt{x}mathrm{d}u$. It will then be $x = (u-1)^2$. Thus, the integral becomes :
$$int (u-1)^2u^3mathrm{d}u ={displaystyleint}u^5,mathrm{d}u-class{steps-node}{cssId{steps-node-2}{2}}{displaystyleint}u^4,mathrm{d}u+{displaystyleint}u^3,mathrm{d}u =dfrac{u^6}{6}-dfrac{2u^5}{5}+dfrac{u^4}{4} + C $$
Now, substitute for $u= sqrt{x} + 1$ and you should get for the initial integral :
begin{align*}
int sqrt{x}(1+sqrt{x}) mathrm{d}x &=dfrac{left(sqrt{x}+1right)^6}{3}-dfrac{4left(sqrt{x}+1right)^5}{5}+dfrac{left(sqrt{x}+1right)^4}{2} + C\
&= boxed{dfrac{left(sqrt{x}+1right)^4left(10x-4sqrt{x}+1right)}{30}+C}.
end{align*}
$endgroup$
$begingroup$
Can we try $ x^{frac{-1}{2}}+1=u $ by taking $sqrt{x}$ common
$endgroup$
– Lakshya Sinha
Dec 17 '18 at 16:05
$begingroup$
@LakshyaSinha What?
$endgroup$
– Rebellos
Dec 17 '18 at 16:05
$begingroup$
Take $ sqrt{x} $ common from cubic term and suppose that as u
$endgroup$
– Lakshya Sinha
Dec 17 '18 at 16:07
$begingroup$
The person who disliked would be kind enough to point out ? The solution is perfectly clear and correct.
$endgroup$
– Rebellos
Dec 18 '18 at 18:42
add a comment |
$begingroup$
By parts $u=(1+sqrt{x})^3$ and $v'=sqrt{x}$:
$$int sqrt{x}left(1+sqrt{x}right)^3dx=frac{2}{3}x^{frac{3}{2}}left(1+sqrt{x}right)^3-int :xleft(1+sqrt{x}right)^2dx$$
And then by expanding:
$$int :xleft(1+sqrt{x}right)^2dx=frac{x^2}{2}+frac{4}{5}x^{frac{5}{2}}+frac{x^3}{3}$$
So
$$int sqrt{x}left(1+sqrt{x}right)^3dx=frac{2}{3}x^{frac{3}{2}}left(1+sqrt{x}right)^3-frac{x^2}{2}-frac{4}{5}x^{frac{5}{2}}-frac{x^3}{3}+C.$$
$endgroup$
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Let $u = sqrt{x}+1 implies mathrm{d}x = 2sqrt{x}mathrm{d}u$. It will then be $x = (u-1)^2$. Thus, the integral becomes :
$$int (u-1)^2u^3mathrm{d}u ={displaystyleint}u^5,mathrm{d}u-class{steps-node}{cssId{steps-node-2}{2}}{displaystyleint}u^4,mathrm{d}u+{displaystyleint}u^3,mathrm{d}u =dfrac{u^6}{6}-dfrac{2u^5}{5}+dfrac{u^4}{4} + C $$
Now, substitute for $u= sqrt{x} + 1$ and you should get for the initial integral :
begin{align*}
int sqrt{x}(1+sqrt{x}) mathrm{d}x &=dfrac{left(sqrt{x}+1right)^6}{3}-dfrac{4left(sqrt{x}+1right)^5}{5}+dfrac{left(sqrt{x}+1right)^4}{2} + C\
&= boxed{dfrac{left(sqrt{x}+1right)^4left(10x-4sqrt{x}+1right)}{30}+C}.
end{align*}
$endgroup$
$begingroup$
Can we try $ x^{frac{-1}{2}}+1=u $ by taking $sqrt{x}$ common
$endgroup$
– Lakshya Sinha
Dec 17 '18 at 16:05
$begingroup$
@LakshyaSinha What?
$endgroup$
– Rebellos
Dec 17 '18 at 16:05
$begingroup$
Take $ sqrt{x} $ common from cubic term and suppose that as u
$endgroup$
– Lakshya Sinha
Dec 17 '18 at 16:07
$begingroup$
The person who disliked would be kind enough to point out ? The solution is perfectly clear and correct.
$endgroup$
– Rebellos
Dec 18 '18 at 18:42
add a comment |
$begingroup$
Let $u = sqrt{x}+1 implies mathrm{d}x = 2sqrt{x}mathrm{d}u$. It will then be $x = (u-1)^2$. Thus, the integral becomes :
$$int (u-1)^2u^3mathrm{d}u ={displaystyleint}u^5,mathrm{d}u-class{steps-node}{cssId{steps-node-2}{2}}{displaystyleint}u^4,mathrm{d}u+{displaystyleint}u^3,mathrm{d}u =dfrac{u^6}{6}-dfrac{2u^5}{5}+dfrac{u^4}{4} + C $$
Now, substitute for $u= sqrt{x} + 1$ and you should get for the initial integral :
begin{align*}
int sqrt{x}(1+sqrt{x}) mathrm{d}x &=dfrac{left(sqrt{x}+1right)^6}{3}-dfrac{4left(sqrt{x}+1right)^5}{5}+dfrac{left(sqrt{x}+1right)^4}{2} + C\
&= boxed{dfrac{left(sqrt{x}+1right)^4left(10x-4sqrt{x}+1right)}{30}+C}.
end{align*}
$endgroup$
$begingroup$
Can we try $ x^{frac{-1}{2}}+1=u $ by taking $sqrt{x}$ common
$endgroup$
– Lakshya Sinha
Dec 17 '18 at 16:05
$begingroup$
@LakshyaSinha What?
$endgroup$
– Rebellos
Dec 17 '18 at 16:05
$begingroup$
Take $ sqrt{x} $ common from cubic term and suppose that as u
$endgroup$
– Lakshya Sinha
Dec 17 '18 at 16:07
$begingroup$
The person who disliked would be kind enough to point out ? The solution is perfectly clear and correct.
$endgroup$
– Rebellos
Dec 18 '18 at 18:42
add a comment |
$begingroup$
Let $u = sqrt{x}+1 implies mathrm{d}x = 2sqrt{x}mathrm{d}u$. It will then be $x = (u-1)^2$. Thus, the integral becomes :
$$int (u-1)^2u^3mathrm{d}u ={displaystyleint}u^5,mathrm{d}u-class{steps-node}{cssId{steps-node-2}{2}}{displaystyleint}u^4,mathrm{d}u+{displaystyleint}u^3,mathrm{d}u =dfrac{u^6}{6}-dfrac{2u^5}{5}+dfrac{u^4}{4} + C $$
Now, substitute for $u= sqrt{x} + 1$ and you should get for the initial integral :
begin{align*}
int sqrt{x}(1+sqrt{x}) mathrm{d}x &=dfrac{left(sqrt{x}+1right)^6}{3}-dfrac{4left(sqrt{x}+1right)^5}{5}+dfrac{left(sqrt{x}+1right)^4}{2} + C\
&= boxed{dfrac{left(sqrt{x}+1right)^4left(10x-4sqrt{x}+1right)}{30}+C}.
end{align*}
$endgroup$
Let $u = sqrt{x}+1 implies mathrm{d}x = 2sqrt{x}mathrm{d}u$. It will then be $x = (u-1)^2$. Thus, the integral becomes :
$$int (u-1)^2u^3mathrm{d}u ={displaystyleint}u^5,mathrm{d}u-class{steps-node}{cssId{steps-node-2}{2}}{displaystyleint}u^4,mathrm{d}u+{displaystyleint}u^3,mathrm{d}u =dfrac{u^6}{6}-dfrac{2u^5}{5}+dfrac{u^4}{4} + C $$
Now, substitute for $u= sqrt{x} + 1$ and you should get for the initial integral :
begin{align*}
int sqrt{x}(1+sqrt{x}) mathrm{d}x &=dfrac{left(sqrt{x}+1right)^6}{3}-dfrac{4left(sqrt{x}+1right)^5}{5}+dfrac{left(sqrt{x}+1right)^4}{2} + C\
&= boxed{dfrac{left(sqrt{x}+1right)^4left(10x-4sqrt{x}+1right)}{30}+C}.
end{align*}
edited Dec 17 '18 at 15:54
Christoph
12.5k1642
12.5k1642
answered Dec 17 '18 at 15:43
RebellosRebellos
15.3k31250
15.3k31250
$begingroup$
Can we try $ x^{frac{-1}{2}}+1=u $ by taking $sqrt{x}$ common
$endgroup$
– Lakshya Sinha
Dec 17 '18 at 16:05
$begingroup$
@LakshyaSinha What?
$endgroup$
– Rebellos
Dec 17 '18 at 16:05
$begingroup$
Take $ sqrt{x} $ common from cubic term and suppose that as u
$endgroup$
– Lakshya Sinha
Dec 17 '18 at 16:07
$begingroup$
The person who disliked would be kind enough to point out ? The solution is perfectly clear and correct.
$endgroup$
– Rebellos
Dec 18 '18 at 18:42
add a comment |
$begingroup$
Can we try $ x^{frac{-1}{2}}+1=u $ by taking $sqrt{x}$ common
$endgroup$
– Lakshya Sinha
Dec 17 '18 at 16:05
$begingroup$
@LakshyaSinha What?
$endgroup$
– Rebellos
Dec 17 '18 at 16:05
$begingroup$
Take $ sqrt{x} $ common from cubic term and suppose that as u
$endgroup$
– Lakshya Sinha
Dec 17 '18 at 16:07
$begingroup$
The person who disliked would be kind enough to point out ? The solution is perfectly clear and correct.
$endgroup$
– Rebellos
Dec 18 '18 at 18:42
$begingroup$
Can we try $ x^{frac{-1}{2}}+1=u $ by taking $sqrt{x}$ common
$endgroup$
– Lakshya Sinha
Dec 17 '18 at 16:05
$begingroup$
Can we try $ x^{frac{-1}{2}}+1=u $ by taking $sqrt{x}$ common
$endgroup$
– Lakshya Sinha
Dec 17 '18 at 16:05
$begingroup$
@LakshyaSinha What?
$endgroup$
– Rebellos
Dec 17 '18 at 16:05
$begingroup$
@LakshyaSinha What?
$endgroup$
– Rebellos
Dec 17 '18 at 16:05
$begingroup$
Take $ sqrt{x} $ common from cubic term and suppose that as u
$endgroup$
– Lakshya Sinha
Dec 17 '18 at 16:07
$begingroup$
Take $ sqrt{x} $ common from cubic term and suppose that as u
$endgroup$
– Lakshya Sinha
Dec 17 '18 at 16:07
$begingroup$
The person who disliked would be kind enough to point out ? The solution is perfectly clear and correct.
$endgroup$
– Rebellos
Dec 18 '18 at 18:42
$begingroup$
The person who disliked would be kind enough to point out ? The solution is perfectly clear and correct.
$endgroup$
– Rebellos
Dec 18 '18 at 18:42
add a comment |
$begingroup$
By parts $u=(1+sqrt{x})^3$ and $v'=sqrt{x}$:
$$int sqrt{x}left(1+sqrt{x}right)^3dx=frac{2}{3}x^{frac{3}{2}}left(1+sqrt{x}right)^3-int :xleft(1+sqrt{x}right)^2dx$$
And then by expanding:
$$int :xleft(1+sqrt{x}right)^2dx=frac{x^2}{2}+frac{4}{5}x^{frac{5}{2}}+frac{x^3}{3}$$
So
$$int sqrt{x}left(1+sqrt{x}right)^3dx=frac{2}{3}x^{frac{3}{2}}left(1+sqrt{x}right)^3-frac{x^2}{2}-frac{4}{5}x^{frac{5}{2}}-frac{x^3}{3}+C.$$
$endgroup$
add a comment |
$begingroup$
By parts $u=(1+sqrt{x})^3$ and $v'=sqrt{x}$:
$$int sqrt{x}left(1+sqrt{x}right)^3dx=frac{2}{3}x^{frac{3}{2}}left(1+sqrt{x}right)^3-int :xleft(1+sqrt{x}right)^2dx$$
And then by expanding:
$$int :xleft(1+sqrt{x}right)^2dx=frac{x^2}{2}+frac{4}{5}x^{frac{5}{2}}+frac{x^3}{3}$$
So
$$int sqrt{x}left(1+sqrt{x}right)^3dx=frac{2}{3}x^{frac{3}{2}}left(1+sqrt{x}right)^3-frac{x^2}{2}-frac{4}{5}x^{frac{5}{2}}-frac{x^3}{3}+C.$$
$endgroup$
add a comment |
$begingroup$
By parts $u=(1+sqrt{x})^3$ and $v'=sqrt{x}$:
$$int sqrt{x}left(1+sqrt{x}right)^3dx=frac{2}{3}x^{frac{3}{2}}left(1+sqrt{x}right)^3-int :xleft(1+sqrt{x}right)^2dx$$
And then by expanding:
$$int :xleft(1+sqrt{x}right)^2dx=frac{x^2}{2}+frac{4}{5}x^{frac{5}{2}}+frac{x^3}{3}$$
So
$$int sqrt{x}left(1+sqrt{x}right)^3dx=frac{2}{3}x^{frac{3}{2}}left(1+sqrt{x}right)^3-frac{x^2}{2}-frac{4}{5}x^{frac{5}{2}}-frac{x^3}{3}+C.$$
$endgroup$
By parts $u=(1+sqrt{x})^3$ and $v'=sqrt{x}$:
$$int sqrt{x}left(1+sqrt{x}right)^3dx=frac{2}{3}x^{frac{3}{2}}left(1+sqrt{x}right)^3-int :xleft(1+sqrt{x}right)^2dx$$
And then by expanding:
$$int :xleft(1+sqrt{x}right)^2dx=frac{x^2}{2}+frac{4}{5}x^{frac{5}{2}}+frac{x^3}{3}$$
So
$$int sqrt{x}left(1+sqrt{x}right)^3dx=frac{2}{3}x^{frac{3}{2}}left(1+sqrt{x}right)^3-frac{x^2}{2}-frac{4}{5}x^{frac{5}{2}}-frac{x^3}{3}+C.$$
answered Dec 17 '18 at 15:47
orangeorange
687315
687315
add a comment |
add a comment |
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$begingroup$
Do you mean $$int sqrt{x} cdot left(1+sqrt{x}right)^3;?$$
$endgroup$
– Chinnapparaj R
Dec 17 '18 at 15:35
$begingroup$
Yes,thanks for correcting
$endgroup$
– Arif Rustamov
Dec 17 '18 at 15:40
3
$begingroup$
Mutliply out the cube to get four terms. Multiply through by the square root. Then you have an easy sum of powers.
$endgroup$
– Ethan Bolker
Dec 17 '18 at 15:40
3
$begingroup$
Why exactly would you not want to expand the integrand?
$endgroup$
– KM101
Dec 17 '18 at 15:42
1
$begingroup$
If you do a substitution you will still have parentheses that need opening: you may get three rather than four terms, but at the cost of the substitution, and for an indefinite integral the cost of re-substitution
$endgroup$
– Henry
Dec 17 '18 at 15:55