Questions about exponentiation, the operation of raising a base $b$ to an exponent $a$ to give $b^a$.

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0
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1answer
27 views

Power function and involution $f(x) = x^a$

For power functions we have a variable $x$ and a constant $a$; we get that $f(x) = x^a$. Find all involutions for $f(x)$. I started out with basic functions such as $f_1(x) = f_1^{-1}(x) = x^1$ and ...
2
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3answers
134 views

Is there a shortcut for raising 2 to the power of a number (e.g. $2^{27}$)?

In networking, when dealing with subnetting, you convert the net mask to binary and count the number of ones (for the example in the question there would be $27$ $1$'s) and to figure out how many ...
1
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3answers
73 views

How can we prove that the square root of any number is equal to the statment given below

Is there any theorem that can explain this $\sqrt[n]{x}= x^{1/n} $, is there any practical example of $ x^{1/n} $, 1/n times of a number.
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0answers
29 views

Relationship of powers of Phi to Lucas Numbers

I was watching a Numberphile and the interviewee was explaining various attributes of Lucas Numbers and he made the statement about creating a sequence by starting with the Golden Ratio and raising it ...
0
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1answer
10 views

Confusion in “mask bits”

This is the question: By definition of the IEEE754 standard, 32-bit floating point numbers are represented as follows: S (1 bit) E (8 bits) M (23 bits) S: Sign bit E: Exponent M: ...
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2answers
27 views

Simplify an expression involving indices

One of my friends asked me this question: Simplify $$\frac{50^{3x-1} 10^{2-3x}}{250^{3x+1}}$$ I've been thinking about the question for more than a day. I've looked through my teacher's notes but ...
1
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2answers
48 views

Solving equations with fractional indices

How would I go about solving an equation like this? $3^{4/3}b^{5/3} - b^3 = 1$ I thought about rearranging to get $3^{4/5}b = (1 + b^3)^{3/5}$, but that didn't seem to lead anywhere as I couldn't ...
0
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2answers
21 views

Exponents with the power being a negative/decimal?

How would I do the equation $b^{n}$ Or $b^{-n}$ Where $b$ is the base, and $n$ in a negative/decimal?
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6answers
2k views

What's the inverse operation of exponents?

You know, like addition is the inverse operation of subtraction, vice versa, multiplication is the inverse of division, vice versa , square is the inverse of square root, vice versa. What's the ...
0
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1answer
46 views

Irrational power of root

Let $a$ and $b$ be rational numbers, such that $\sqrt{a}$ and $\sqrt{b}$ are irrational. Can $\sqrt{a}^\sqrt{b}$ be rational? I found examples, where the irrational power of an irrational number is ...
0
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1answer
76 views

Simplifying $2^\sqrt{\log x}$

Can this expression be simplified? $$2^\sqrt{\log x}$$ Thank you
1
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2answers
40 views

Power of very big numbers

So, I was solving a question, and I came across this. If I have, x=a^b, and If I want to calculate the last digit of x, then it ...
1
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4answers
79 views

$4^{x}+2^{x+1}=18$ Please help me solve?

I tried using logs on both sides or tried treating it as a quadratic but didn't manage to simplify it, Help?:D
0
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1answer
17 views

exponential equation (solve for x)

We started review in my calculus class and I have mostly forgotten everything about exponential equations. $$ e^{-x} * (3e^{2x}-(5/4))^{1/2} = e^x $$ Would x just equal 0, when -x+x=0 (two sides of ...
1
vote
1answer
64 views

is there any solution for $x^2 +x + 2 = e^x$ by using algebra?

I know this can be solved by numerical methods but I would like to know whether this can be solved using logs or something similar. Thanks
2
votes
3answers
144 views

Matrix exponential: Formal notation for power series? Or, more?

For a square matrix $A$, I'm already used to see and use: $$\sum_{n=0}^{\infty} \frac{A^n}{n!} = \lim_{n \to \infty} \left(I + \frac{A}{n}\right)^n = e^A$$ Which means a matrix $A$ is just like some ...
1
vote
2answers
37 views

Negative Number raised to fractional power

How would you solve a negative number raised to a fraction a/b if b is odd and a is evem? Ignoring imaginary numbers i.e $(-1)^\frac23$ Calculator returns an error $(-1)^\frac 13 (-1)^\frac 13$ = ...
0
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1answer
79 views

Can $x^2 +x + 2 = 10^x$ be solved using algebra?

I know this can be solved by numerical methods but I would like to know whether this can be solved using logs or something similar. Thanks
1
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2answers
44 views

Exponential equations with variables on both sides

I have the following: $$8^{3x+4} = 5^{4x-2}$$ How would I solve this? I tried this: $$(3x+4)\log 8 = (4x-2)\log 5$$ but have no idea where to go from there. Thank you!
0
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1answer
16 views

calculating a decrease at constant instantaneous rate

If we have a value e.g. $$ B = 20000 $$ and it decreases at a constant instantaneous rate of say $$ -1.1*10^{-2} $$ per unit time. What would B look like over say 300 time units, and how do we ...
0
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1answer
50 views

How to find the common base of terms in an expression?

I'm teaching myself basic algebra from a book and am stuck on a question. In the current section it is about expressing numbers as powers of the same base. So $9$ maybe expressed as $3^2$. Another ...
0
votes
1answer
18 views

Plotting nth root of x against nx on a graph.

I've spent the last two days trying to figure this out. What I'm trying to do is rearrange this: $$ x^n = \frac xn $$ to make n the subject, to allow me to plot on a graph, with n being the ...
1
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1answer
25 views

Sign of Fractional Exponents

When calculating a number to a fractional exponent or fractional nth root, in what cases is there both a positive and negative solution as opposed to just a positive or just a negative solution?
6
votes
1answer
82 views

How easy is it to prove that if $2^x,3^x, 5^x, 7^x, 11^x … $ are all integers then $x$ is an integer as well?

How easy is it to prove that if $2^x,3^x, 5^x, 7^x, 11^x ... $ are integers then $x$ is an integer as well? I have read the definition of the exponent functions as given in my calculus text, and the ...
1
vote
1answer
32 views

exponentials with different base

What rule can I use when solving exponentials like this one $\frac {2^6 \cdot 5^8 \cdot 3}{100^3}$ I know how to solve exponentials when the bas number is the same with these formulas $x^m \cdot x^n ...
2
votes
2answers
56 views

Unit Quaternion to a Scalar Power

I'm trying to modify a physics engine for efficiency. Currently, as objects move around the world, their orientation (a quaternion) is updated every frame, by multiplying by the rotation (another ...
1
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0answers
58 views

How to prove that $b^{x+y} = b^x b^y$ using this approach?

Fix $b>1$. If $m$, $n$, $p$, $q$ are integers, $n > 0$, $q > 0$, $r = m/n = p/q$, then I can prove that $(b^m)^{1/n} = (b^p)^{1/q}$. Hence it makes sense to define $b^r = (b^m)^{1/n}$. I ...
0
votes
1answer
31 views

From an expression raised in a power of 2 to an expression raised in the power or 10

Is there a simple/"easy" way to convert a big number from a power of $2$ to a power of $10$ equivalent. Example: I had $2^{127}\cdot 1.9999999$ which I did the multiplication got the result and from ...
0
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4answers
43 views

Why is a Constant added to front?

I made the differential equation : $$dQ = (-1/100)2Q dt$$ I separate it and get: $\int_a^b x (dQ/Q) = \int_a^b x (-2/100)dt$ this leads me to: $\log(|Q|) = (-t/50) + C$ I simplify that to $Q = ...
0
votes
1answer
45 views

Big-Oh of exponent of exponent

How does one whether an exponent of an exponent is the big-Oh of the other? For example, if I have $a^{b^n}$ and $b^{a^n}$, how would i determine and prove which is a big oh of another? I'm thinking ...
3
votes
4answers
73 views

Existence of solution in $x,y \in (a,b)$ of $ \bigg(\dfrac { a+b}2\bigg)^{x+y}=a^xb^y$

Let $a<b$ be positive real numbers , then is it true that there exist $x,y \in (a,b)$ such that $ \bigg(\dfrac { a+b}2\bigg)^{x+y}=a^xb^y$ ?
0
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1answer
39 views

Methods to calculate powers in my head

How can i calculate powers in my head, like small powers. for example $0.5^3$, how can i work this out quickly and easily? or $4^5$
1
vote
1answer
56 views

Definition of $z^0, z=a+bi, a,b \in \mathbb{R}, z \neq 0$

Today I found in a True-False the question; Does the equality $$z^0=1, z=a+bi, a,b \in \mathbb{R}$$ hold $\forall z \in \mathbb{C^*}$? The thing is, this was never clearly defined in the book, and ...
3
votes
0answers
26 views

Iterations $n, n^n, (n^n)^{(n^n)},…$

(Note: I'm reposting this, as I posted the original too late in the evening to gain anyone's notice.) A contest problem (#2 on the 2010 Virginia Tech Math Competition) proffers the solver the ...
4
votes
2answers
97 views

Solve the equation: $1+2^x+4^x+8^x+16^x+32^x=3(1+2^x+4^x)$

I am doing some math repetition and am a bit stuck on this exercise: Solve the equation: $1+2^x+4^x+8^x+16^x+32^x=3(1+2^x+4^x)$. Now, this is a geometric sum on both the $LHS$ and $RHS$, which I ...
1
vote
1answer
91 views

Can matrix exponentials ever be negative? If so, under what conditions?

Let $C$ be a $2 \times 2$ matrix with real entries, and $x\in\mathbb{R}^2$. We write $x > 0$ if both coordinates are strictly positive. Suppose $x>0$, under what conditions on $C$ and $x$ ...
-5
votes
4answers
114 views

Computing $0.0625^{-2.25}$ without a calculator

It is quite easy to see that $0.0625^{-2.25} = 512$ by plugging this into a calculator. Of course, mathematics existed for millennia before the invention of the calculator; is there a way to compute ...
0
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1answer
21 views

Complete the square for exponents

How does exp(2x)-2+exp(-2x) = (exp(x) - exp(-x))^2 I am having trouble using complete the square
-1
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2answers
63 views

If a matrix is non diagonalizable, what other method can I use to calculate the nth power?

First off, I have this matrix A: 1 0 3 1 0 2 0 5 0 I have calculated the eigenvalues, which are ...
1
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1answer
34 views

exponent y=x^a sequences.

While analyzing square and cube functions, i found the following: ...
0
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1answer
61 views

How does one obtain the expansion of $e^{-x^2}$ in a power series?

So I know that the Power Series $y = \displaystyle\sum_{m=0}^\infty\displaystyle\frac{(-1)^m}{m!} x^{2m}$ is equivalent to $e^{-x^2}$. Could someone show me why this is?
1
vote
0answers
36 views

Exponential of a power of the differential operator

In relation to this question: Exponential of a polynomial of the differential operator Is there an expression for $\exp(aD^n)f(x)$ similar to $\exp(aD)f(x)=f(x+a)$?
1
vote
3answers
44 views

Easy exponentiation method

Is there a simple way of solving, say, x^(3/2)? For example, one way of solving 16^(3/2) is to calculate the square root of 16^3, but I was wondering if there is a simpler mental trick for doing this ...
1
vote
3answers
116 views

How to calculate power of a number with decimal exponent programatically?

I am trying to code and algorithm that can allow me to calculate power of a function with decimal exponent. The language that I am using to code in doesn't has any predefined power functions. I ...
3
votes
4answers
96 views

If $q^n$ is irrational for all $n>1$, then $q$ is irrational.

Theorem. Let $q \in \mathbb{R}$ an arbitrary given number. If $q^n$ is irrational for all $n>1$ integer, then $q$ is irrational. My Questions. What is a the name of this statement and what is the ...
1
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1answer
63 views

Showing that $\exp(\sum_{n=1}^\infty a_nX^n)=\prod_{n=1}^\infty\exp(a_nX^n)$ for formal power series

I've just come across formal power series and am not very fluent with them yet. I'd like to show that $\exp(\sum_{n=1}^\infty a_nX^n)=\prod_{n=1}^\infty\exp(a_nX^n)$. Can anybody help?
0
votes
2answers
28 views

Why is this term $=1$

Can you tell me why $$\frac{1}{r} \sum_{k=0}^{r-1} R_N(x^k) \sum_{s=0}^{r-1} e^{\frac{-2 \pi i s k}{r}}=1?$$ Here $R_N(x^k)$ is the remainder of $x^k$ Modulo $N$. When I entered the last sum in ...
0
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1answer
36 views

How to divide $6^{4/6}$ by $6^{6/8}$?

How do you resolve this: base 6 and exponent 4/6 divided by base 6 and exponent 6/8?
2
votes
6answers
82 views

Why is the result of $-2^2 = -4$ but $(-2)^2 =4$?

I am really new into math, why is $-2^2 = -4 $ and $(-2)^2 = 4 $?
0
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2answers
32 views

Distributing exponents to variables [duplicate]

I am studying parabolas, but the way exponents are distributed is confusing me to oblivion. $(y_2 – 2)^2$ $y_2^2 – 4y_2^2 + 4$ I do not understand how can the first expression be simplified to the ...