Get Answers to all your Questions

header-bg qa

The value of \int x. \; \frac{ln(x+\sqrt{1+x^{2}})}{\sqrt{1+x^{2}}} dx  equals

Option: 1

\sqrt{1+x^{2}}\; ln(x+\sqrt{1+x^{2}})-x+C


Option: 2

\frac{x}{2}.ln^{2}(x+\sqrt{1+x^{2}})-\frac{x}{\sqrt{1+x^{2}}}+C


Option: 3

\frac{x}{2}.ln^{2}(x+\sqrt{1+x^{2}})+\frac{x}{\sqrt{1+x^{2}}}+C


Option: 4

\sqrt{1+x^{2}}\; ln(x+\sqrt{1+x^{2}})+x+C


Answers (1)

best_answer

 

Integration By PARTS -

Let u and v are two functions then 

\int u\cdot vdx=u\int vdx-\int \left ( \frac{du}{dx}\int vdx \right )dx

- wherein

Where u is the Ist function v is he IInd function

 

 

Rule for integration by parts -

Take Ist function (u) as according I L A T E

 

- wherein

Where ,

I : Inverse

L : Logarithmic

A : Algebraic 

T : Trignometric

E : Exponential

 

 

\int x.\frac{ln(x+\sqrt{1+x^{2}})}{\sqrt{1+x^{2}}}dx

I=\int ln(x+\sqrt{1+x^{2}}).\frac{x}{\sqrt{1+x^{2}}}dx

=\sqrt{1+x^{2}} ln(x+\sqrt{1+x^{2}})-\int \frac{1}{\sqrt{1+x^{2}}}.\sqrt{1+x^{2}}dx (using integration by parts)

=\sqrt{1+x^{2}} ln(x+\sqrt{1+x^{2}})-x+C

Alternate:

Let x+\sqrt{1+x^{2}}=e^{t} \; then

(\dfrac{x}{\sqrt{x^2+1}}+1)dx=e^tdt

I=\int x \; t\; dt=\int \frac{(e^{t}-e^{-t})t dt }{2}=\frac{1}{2}t\left ( e^{t}+e^{-1} \right )

-\frac{1}{2}(e^{-t}-e^{-t})+C=\sqrt{1+x^{2}}\;ln\;(x+\sqrt{1+x^{2}})-x+C

Posted by

Divya Prakash Singh

View full answer

JEE Main high-scoring chapters and topics

Study 40% syllabus and score up to 100% marks in JEE