denominator

Simultaneous derivation,

get

( 1

-

e^x^2)

/

(2xsinx

+

x^2

cosx)，

The following can be replaced by law or infinitesimal.

e^x

≈

1

+

x； sinx≈x，cosx≈ 1:

get

(-

x^2

)

/

(2x^2

+

x^2)

=

-

1/3