n
X
n(n + 1)
2
(Arithmetic sum)
n(n + 1)(2n + 1)
6
(Sum of squares)
i=
i=1
n
X
i2 =
i=1
n
X
i3 =
i=1
n
X
n2 (n + 1)2
4
rn+1 − 1
1 − rn+1
=
1−r
r−1
ri =
i=0
∞
X
ri =
i=0
1
1−r
loga (xy) = loga (x) + loga (y)
(Sum of cubes)
(Geometric sum)
(Geometric series)
(1)
n
(2)
loga (a) = 1
(3)
loga (1) = 0
(4)
loga (x ) = n loga (x)
a
loga (n)
logb (n)
a
=n
=n
(5)
logb (a)
1
(6)