integrate pls

Q1. \int \frac{(x^2-1)dx}{(x^4+3x^2+1)tan^-^1\frac{x^2+1}{x}}

6 Answers

62
Lokesh Verma ·

asish.. try x+1/x=t

106
Asish Mahapatra ·

yup got it

thx sir :)

106
Asish Mahapatra ·

Q2. \int sin^1^2xdx

1
Samarth Kashyap ·

well, reduction formula can be used ,
\int sin^{n}x.dx=\frac{-sin^{n-1}x.cosx}{n}+\frac{n-1}{n}\int sin^{n-2}x.dx
but it'll make the prblm really really lengthy...still thinking of some ther method

1
aieeee ·

cn try it another way;
let,z be a complex number. z=cosx + isinx and 1/z = cosx - isinx

now, z-1/z = 2i sinx , (z-1/z)12 = 212 sin12x

now,by expanding (z-1/z)12,we'll get in the form of conjugates

and then putting the expansion of z, sin functions get cancelled out

and cos func. remain( De'Moivre's theorem is used for compact form).

now it cn be integrated.

106
Asish Mahapatra ·

abhisek this was for others to try. dont post tuition material here please

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