Fermi
·
Concept Library
·
Courses
·
Books
·
Problems
·
Simulations
·
Math Wiki
·
High School
Fermi
›
Problems
Mathematics
Mathematics
Problem
Which of the following expresses the sum
S
n
S_n
S
n
of the first
n
n
n
terms of an arithmetic progression whose first term is
a
a
a
and common difference is
d
d
d
? a)
S
n
=
a
+
(
n
−
1
)
d
S_n = a + (n-1)d
S
n
=
a
+
(
n
−
1
)
d
b)
S
n
=
n
[
a
+
(
n
−
1
)
d
]
S_n = n\,[a + (n-1)d]
S
n
=
n
[
a
+
(
n
−
1
)
d
]
c)
S
n
=
n
2
[
2
a
+
(
n
−
1
)
d
]
S_n = \dfrac{n}{2}[2a + (n-1)d]
S
n
=
2
n
[
2
a
+
(
n
−
1
)
d
]
d)
S
n
=
n
2
[
a
+
(
n
−
1
)
d
]
S_n = \dfrac{n}{2}[a + (n-1)d]
S
n
=
2
n
[
a
+
(
n
−
1
)
d
]
Browse the problem library