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Question
Mathematics
If f:R→ R is given by f(x)= beginmatrix -1, when x is rational 1, when x is irrational endmatrix . then (fof) (1-√3) is equal to
Q. If
f
:
R
→
R
is given by
f
(
x
)
=
{
−
1
,
w
h
e
n
x
i
s
r
a
t
i
o
na
l
1
,
w
h
e
n
x
i
s
i
rr
a
t
i
o
na
l
then
(
f
o
f
)
(
1
−
3
)
is equal to
2681
186
J & K CET
J & K CET 2007
Relations and Functions - Part 2
Report Error
A
1
21%
B
−
1
46%
C
3
21%
D
0
12%
Solution:
Given,
f
(
x
)
=
{
−
1
,
w
h
ere
x
i
s
r
a
t
i
o
na
l
1
,
w
h
e
n
x
i
s
i
rr
a
t
i
o
na
l
Now,
(
f
o
f
)
(
1
−
3
)
=
f
[
f
(
1
−
3
)]
=
f
(
1
)
=
−
1