Math, asked by abhijeetvshkrma, 5 months ago

Solve this integral asap​

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Answers

Answered by Flaunt
106

Question

\sf  \large\displaystyle\int \:  {x}^{2}  {e}^{x} dx

\huge\bold{\gray{\sf{Answer:}}}

\bold{Explanation:}

By using ILATE concept :

x² is an algebraic term so it's a first function and e^x is a second function.

By applying Product form of integration we will solve Question :-

 \sf\boxed{\large \displaystyle\int \: u vdx = u\int \: vdx - \displaystyle \int\bigg( \dfrac{d}{dx} u\displaystyle \int \: vdx\bigg)dx}

\large\displaystyle \int {x}^{2}  {e}^{x}  =  {x}^{2}\displaystyle  \int {e}^{x} dx - \displaystyle \int(2x. {e}^{x} dx)

 \sf\large=  {x}^{2}  {e}^{x}  - 2 \displaystyle\int \: x. {e}^{x}  dx

 \sf\large=  {x}^{2}  {e}^{x}  - 2\bigg(x {e}^{x}  - \displaystyle \int1. {e}^{x} dx\bigg)

 \sf\large=  {x}^{2}  {e}^{x}  - 2\bigg(x {e}^{x}  -  {e}^{x}\bigg )

 \sf\large=  {x}^{2}  {e}^{x}  - 2x {e}^{x}  + 2 {e}^{x}


Anonymous: nice explanation
abhijeetvshkrma: can't it be done by substitution rule?
Flaunt: substitution method suitable in definite integral
abhijeetvshkrma: Ok thanks
Answered by vk8091624
0

By using ILATE concept :

x² is an algebraic term so it's a first function and e^x is a second function.

By applying Product form of integration we will solve Question :-

\sf\boxed{\large \displaystyle\int \: u vdx = u\int \: vdx - \displaystyle \int\bigg( \dfrac{d}{dx} u\displaystyle \int \: vdx\bigg)dx}

∫uvdx=u∫vdx−∫(

dx

d

u∫vdx)dx

\large\displaystyle \int {x}^{2} {e}^{x} = {x}^{2}\displaystyle \int {e}^{x} dx - \displaystyle \int(2x. {e}^{x} dx)∫x

2

e

x

=x

2

∫e

x

dx−∫(2x.e

x

dx)

\sf\large= {x}^{2} {e}^{x} - 2 \displaystyle\int \: x. {e}^{x} dx=x

2

e

x

−2∫x.e

x

dx

\sf\large= {x}^{2} {e}^{x} - 2\bigg(x {e}^{x} - \displaystyle \int1. {e}^{x} dx\bigg)=x

2

e

x

−2(xe

x

−∫1.e

x

dx)

\sf\large= {x}^{2} {e}^{x} - 2\bigg(x {e}^{x} - {e}^{x}\bigg )=x

2

e

x

−2(xe

x

−e

x

)

\sf\large= {x}^{2} {e}^{x} - 2x {e}^{x} + 2 {e}^{x}=x

2

e

x

−2xe

x

+2e

x

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