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Mathematics
Problem
Which of the following is the correct expression for the
n
n
n
th term of an arithmetic progression whose first term is
a
a
a
and common difference is
d
d
d
? a)
a
n
=
a
+
n
d
a_n = a + nd
a
n
=
a
+
n
d
b)
a
n
=
n
2
(
2
a
+
(
n
−
1
)
d
)
a_n = \dfrac{n}{2}\bigl(2a + (n-1)d\bigr)
a
n
=
2
n
(
2
a
+
(
n
−
1
)
d
)
c)
a
n
=
a
+
(
n
−
1
)
d
a_n = a + (n-1)d
a
n
=
a
+
(
n
−
1
)
d
d)
a
n
=
a
(
1
+
d
)
n
−
1
a_n = a(1+d)^{\,n-1}
a
n
=
a
(
1
+
d
)
n
−
1
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