Seed5813
New member
- Joined
- Jan 29, 2018
- Messages
- 24
Ok so from y=e^(-x^2) to x=b is being revolved around the y axis and the resulting solid is 3/2 cubic units.
I set up the shell method:
2pi int_0^b (x(e^(-x^2)))dx = 3/2
u=-x^2
du=-2xdx
u at b = -b^3
u at 0 = 0
-pi int_0^(-b^2) (e^u) du = 3/2
-pi [e^(-b^2) - 1] = 3/2
e^(-b^2) - 1 = (-3/2pi)
e^(-b^2) = 1 - (3/2pi)
The right hand term is a negative number so I can't take the natural log of it, so I'm stuck. I can't find my mistake.
Sent from my LGLS755 using Tapatalk
I set up the shell method:
2pi int_0^b (x(e^(-x^2)))dx = 3/2
u=-x^2
du=-2xdx
u at b = -b^3
u at 0 = 0
-pi int_0^(-b^2) (e^u) du = 3/2
-pi [e^(-b^2) - 1] = 3/2
e^(-b^2) - 1 = (-3/2pi)
e^(-b^2) = 1 - (3/2pi)
The right hand term is a negative number so I can't take the natural log of it, so I'm stuck. I can't find my mistake.
Sent from my LGLS755 using Tapatalk