# Find a value for parameter...

• April 27th 2010, 11:29 PM
VinhT
Find a value for parameter...
Find a value for the parameter a that makes the value of the following improper integral less than 0.0001

∫ x^2*e^(-x^3)
a

Somebody can help me ?
• April 28th 2010, 03:37 AM
HallsofIvy
Quote:

Originally Posted by VinhT
Find a value for the parameter a that makes the value of the following improper integral less than 0.0001

∫ x^2*e^(-x^3)
a

Somebody can help me ?

I presume you mean $\int_a^\infty x^2 e^{-x^3}dx$ (The "dx" is important.)

Use the substitution $u= x^3$ to integrate, getting a result that depends on a. Set that equal to 0.0001 and solve for a.