JEE Mains Model Paper 1

Here , y = (1 + x) (1 + x2) (1 + x4) ..... (1 + x2n)
=

1

1−x

{(1 - x) (1 + x) (1 + x2 (1 + x4)) ..... (1 + x2n)}
=

1

1−x

{(1 - x2) (1 + x2) (1 + x4) ..... (1 + x2n)}
=

1

1−x

{(1 - x4) (1 + x4) ...... (1 + x2n)} =

(1−x2n+1)

(1−x)

∴

dy

dx

=
(

dy

dx

)x=0 = −2n+1.(0).(1).+

(1−0)

(1−0)2

= 1