How to find the integral of x 3^(x^2)

  • Thread starter intenzxboi
  • Start date
  • #1
98
0

Homework Statement


[tex]\int[/tex] x 3^(x^2)


Homework Equations



integration by parts

The Attempt at a Solution



u= x dv= 3^(x^2)
du = 1 dx v=((3^(x^2))/ln 3 ) 2x + c ??

(x)((3^(x^2))/ln 3 ) 2x - [tex]\int[/tex] ((3^(x^2))/ln 3 ) 2x dx

is this right??
 

Answers and Replies

  • #2
156
0


Homework Statement


[tex]\int[/tex] x 3^(x^2)


Homework Equations



integration by parts

The Attempt at a Solution



u= x dv= 3^(x^2)
du = 1 dx v=((3^(x^2))/ln 3 ) 2x + c ??
No: what do you get when you differentiate your v? 3^(x^2) doesn't have a nice integral.

Rather, you should recognise [tex]\int x3^{x^2} \, dx[/tex] is built for a substitution: let [tex]u = x^2[/tex].
 
  • #3
98
0


so u=x^2
du = 2x

1/2 3^u du??
 
  • #4
Hitman2-2


so u=x^2
du = 2x

1/2 3^u du??

do you mean

[tex]

\frac{1}{2}\int 3^u du

[/tex]
 
  • #5
98
0


are u sure about this.. people are telling me that i need to integrate by parts
 
  • #6
Hitman2-2


are u sure about this.. people are telling me that i need to integrate by parts

Unco is correct: use the substitution
 
  • #7
HallsofIvy
Science Advisor
Homework Helper
41,833
964


are u sure about this.. people are telling me that i need to integrate by parts
Then stop listening to those people!
 
  • #8
98
0


k gotcha. quick question whats the difference between integrating by parts and u substitution
 

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