Fermi
·
Concept Library
·
Courses
·
Books
·
Problems
·
Simulations
·
Math Wiki
·
High School
Fermi
›
Problems
Mathematics
Mathematics
Problem
Which of the following conditions exactly characterises a one–one function
f
:
X
→
Y
f:X \to Y
f
:
X
→
Y
? a) If
x
1
=
x
2
x_1=x_2
x
1
=
x
2
, then
f
(
x
1
)
=
f
(
x
2
)
f(x_1)=f(x_2)
f
(
x
1
)
=
f
(
x
2
)
b) Every vertical line meets the graph of
f
f
f
at most once c) If
f
(
x
1
)
=
f
(
x
2
)
f(x_1)=f(x_2)
f
(
x
1
)
=
f
(
x
2
)
, then
x
1
=
x
2
x_1=x_2
x
1
=
x
2
d)
f
f
f
is both one–one and onto
Browse the problem library