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Unlike Differentiation, you cannot perform the operation of Integration on combinations of functions. Hence, in order to integrate such functions, we use a method called Integration by parts.
Here, we try to split the given function into 2 separate functions, taking one as 'u' and the other as 'dv'. Deriving a formula from the product rule of differentiation, we can evaluate the integral as,
d (uv) = u.dv - v.du
Integrating on both sides...
∫d (uv) = ∫u.dv - ∫v.du
uv = ∫u.dv - ∫v.du
∫u.dv = uv - ∫v.du
The above equation gives us the formula for Integration by parts.
The order of priority to take a given function as 'u' is in the following order, which can be remembered as a mnemonic ILATE
I - Inverse
L - Logarithmic
A - Algebraic
T - Trigonometric
E - Exponential
Now, let us integrate the function you have given...
∫x * e^x . dx
According to ILATE,
u = x (an algebraic function), dv = e^x . dx (an exponential function)
∫u.dv = uv - ∫v.du
∫x * e^x . dx = uv - ∫v.du --------------------- (i)
u = x
Differentiating...
=> du = 1 . dx = dx { d(x^n) = n * x^(n-1) }
dv = e^x . dx
Integrating...
=> ∫dv = ∫e^x . dx
=> v = e^x { ∫e^(ax+b).dx = e^(ax+b) / a }
Now substituting the values in (i)...
∫x * e^x . dx = uv - ∫v.du
=> ∫x * e^x . dx = x * e^x - ∫e^x . dx
=> ∫x * e^x . dx = x * e^x - e^x
=> ∫x * e^x . dx = e^x [x - 1]
Therefore,
∫x * e^x . dx = e^x [x - 1] + c
- where c is the constant of integration.
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2007-01-30 21:53:45
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answer #1
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answered by Preety 2
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Formula for integration by parts is:-
I = Int(udv/dx)dx = uv - Int (vdu/dx)dx
where u = x and dv/dx = e^x
du/dx = 1 and v = e^x
I = xe^x - Int(e^x) + c
I = xe^x - e^x + c
I = e^x(x - 1) + c
Unlike Preety i am not majoring in maths, but i would sure like to know how to get the integral sign she uses instead of having to write Int all the time!
2007-01-30 22:28:37
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answer #2
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answered by Como 7
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Integral (x e^x ) dx
You have to use integration by parts to solve this.
Let u = x. dv = e^x dx
du = dx. v = e^x
Therefore
uv - Integral (v du)
x e^x - Integral (e^x) dx
x e^x - e^x + C
2007-01-30 19:43:29
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answer #3
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answered by Puggy 7
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The crucial of e^x is e^x. it is one reason the consistent e is so particular, and maximum every physique is taught that common crucial in calculus. crucial(e^x-e)dx=crucial(e^x)dx-integr... crucial of e is e*x (e is a relentless, comparable as e*x^0, use the flexibility rule, a million*e*x^a million=e*x) so it fairly is e^x-e*x+c (c being a relentless on account that this wasn't a different crucial)
2016-12-13 05:08:14
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answer #4
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answered by Anonymous
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From the product rule of differentiation we can deduce a formula for integration by parts. Let u=x and dv/dx = e^x
int. u(dv/dx) dx = uv - int. v(du/dx) dx
then,
int. x.e^x dx = xe^x - int. e^x dx = e^x (x - 1) + c
2007-01-30 21:42:45
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answer #5
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answered by yasiru89 6
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(x-1)e^x
2007-01-30 19:42:57
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answer #6
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answered by Scythian1950 7
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int(x*e^x)dx===>
es una integral por partes este es el método
f*g´-int(g*f´)
f=x --->f´=dx
g´=e^x -->g=e^x (la int de e^u=e^u)
sust valores
x*e^x- int(e^x dx)= x*e^x-e^x+C
2007-01-30 20:14:11
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answer #7
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answered by Anonymous
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suppose I(x) is integral sign!
from the formula e^x=(e^x)'
I(x*e^xdx)=
=I(x*(e^x)'*dx)=
=x*e^x-I(x'*e^x*dx)=
=x*e^x-I(e^x*dx)=
=x*e^x-e^x
=e^x(x-1)
2007-01-30 20:11:45
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answer #8
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answered by happyrabbit 2
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