unsorted dependencies
exponentiation
Suppose , and
n
∈
N
1
, then
b
n
:=
b
⋅
b
⋅
…
⋅
b
⋅
b
⏟
n
times
, note that
b
n
:
N
1
→
R
exponentiation of a positive number is positive
Suppose that
x
∈
R
>
0
, then
x
n
∈
R
>
0
product of two reals of the same sign is positive
Given
x
,
y
∈
R
, if
x
,
y
<
0
or
x
,
y
>
0
, then
x
⋅
y
=
0
multiplicative inverse
Suppose that
x
∈
R
≠
0
, then if
w
∈
R
satisfies
x
⋅
w
=
1
, then it is said to be the reciprocal or multiplicative inverse of
x
and we write
w
=
1
x
Suppose that
n
∈
N
1
and
f
:
R
>
0
→
R
is defined as
f
(
x
)
=
x
n
, then
f
is strictly increasing.
Suppose that
n
∈
N
1
and
x
∈
R
>
0
, then
x
n
>
0
(TODO: product of two numbers of the same sign is positive and induction.)
Suppose that
a
,
b
,
c
∈
R
, with
a
<
b
and
c
>
0
, then
a
c
<
b
c
Suppose that
a
n
,
b
n
are two real sequences and that
∑
n
=
0
∞
a
n
and
∑
n
=
0
∞
b
n
are convergent series, if for each
n
∈
N
,
a
n
<
b
n
, then
∑
n
=
1
∞
Suppose
x
,
y
∈
R
with the same sign. Then
x
<
y
if and only if
1
y
≤
1
x
binomial
Suppose that
x
,
y
∈
R
such that
x
+
y
≥
0
and that
n
∈
N
0
, then
(
x
+
y
)
n
=
∑
k
=
0
n
(
n
k
)
x
n
−
k
y
k
TODO
exponential function
exponential
e
x
:=
∑
k
=
0
∞
x
k
k
!
, note that
e
x
:
R
→
R
and that
x
k
is exponentiation. We say that
e
x
is the exponential.
e
x
=
lim
n
→
∞
(
1
+
x
n
)
n
TODO
d
d
x
[
e
x
]
=
e
x
d
d
x
=
lim
h
→
0
e
x
+
h
−
e
x
h
=
lim
h
→
∞
lim
n
→
∞
(
1
+
x
+
h
n
)
n
−
lim
n
→
∞
(
1
+
x
n
)
n
h
=
lim
h
→
0
(
lim
n
→
∞
(
1
+
x
+
h
n
)
n
−
(
1
+
x
n
)
n
h
)
Therefore by the binomial theorem...
exponential sum product equality
Suppose
x
,
y
∈
R
, then
e
x
+
y
=
e
x
⋅
e
y
TODO
reciprocal of exponential
1
e
x
=
e
−
x
e
0
=
1
as if we sub in
x
=
0
e
x
=
∑
n
=
0
∞
x
n
n
!
, and we know that
0
0
is defined to be
0
, then
e
0
=
1
But at the same time
e
0
=
e
x
−
x
which equals
e
x
⋅
e
−
x
=
1
, so thus
1
e
x
=
e
−
x
as needed.
x
<
0
,iff
e
x
<
1
since
e
x
is increasing it's fine (TODO finish)
0
<
x
<
1
iff
ln
(
x
)
<
0
TODO
exponential is always positive
∀
x
∈
R
,
e
x
>
0
If
x
>
0
, then by one of the unordered dependencies we have
x
n
>
0
, then by one of the unorder dependencies about real numbes since
1
n
!
>
0
we have
x
n
n
!
>
0
n
!
=
0
and using
x
n
n
!
=
∑
n
=
0
∞
a
n
with
a
i
=
0
for
i
∈
{
0
,
…
,
n
−
1
}
and
a
n
=
x
n
n
!
and
b
i
=
x
i
i
!
the comparison test tells us that
0
<
e
x
If
x
<
0
, then
−
x
>
0
, and thus by the above argumnet
0
<
e
−
x
=
1
e
x
, recall that
e
−
x
⋅
e
x
=
1
, and we know that
e
−
x
and
1
are positive so therefore
e
x
>
0
as well, as needed.
If
x
=
0
, then
e
x
=
e
0
=
1
logarithm
Suppose that
a
,
b
∈
R
, then
m
=
log
b
(
a
)
is a number such that
b
m
=
a
natural logarithm
We define
ln
(
x
)
:=
log
e
(
x
)
and call it the natural logarithm.
∀
r
∈
R
,
r
x
:=
e
ln
(
r
)
⋅
x
exponentiation inverse
given
r
∈
R
, then the multiplicative inverse of
r
x
is
r
−
x
TODO
Suppose that
0
<
r
<
1
and
x
∈
R
>
0
, then
0
<
r
x
<
1
TODO
Let
a
,
b
∈
R
>
0
and assume that
a
<
b
, then if
0
<
r
<
1
, then
r
a
>
r
b
Since
a
<
b
, then
0
<
b
−
a
, and thus