Positive Definition and 964 Threads

Homework Statement Find 3 positive numbers x, y and z for which: their sum is 24 and which maximizes the product: P = x2y3z. Find the maximum product. The Attempt at a Solution Ok, I know how to set up the equations. x + y + z = 24 Delta(F) <2xy3z, 2x2y2z, x2y3> fx = 2xy3z...

Homework Statement Let k be any positive integer. Prove that there exists a positive integer multiple n of k such that the only digits in n are 0s and 1s. (Use the pigeonhole principle.) Homework Equations The General Pigeonhole Principle If more than mk things are distributed into k...

Homework Statement How many coulombs of positive charge are in 1.91 mol of O2 gas? Homework Equations 1 mol = 6.022x10^23 protons q=Ne The Attempt at a Solution so 1.91 mols x 6.022x10^23 = 1.1502x10^24 protons I divided that by 6.25x10^18 protons in one coulomb, but I got...

most of the cosmic rays that hit the Earth is made up of positively charged particles, like protons. This suggests that the Earth has a growing excess of positive charge ... Is this true?

Homework Statement Is it possible to construct a field, that satisfies all basic propeties (http://en.wikipedia.org/wiki/Field_%28mathematics%29#Definition_and_illustration , the six bolded part ), with only and all positive integers? Remeber, you don't have 0/negative numbers/fraction in...

Can electricity be positive instead of negative? What differences would it be? Can electricity be used to repel things?

Here is my problem. Any ideas are appreciated. Let P be a projection matrix (symmetric, idempotent, positive semidefinite with 0 or 1 eigenvalues). For example, P = X*inv(X'*X)*X' where X is a regressor matrix in a least square problem. Let A be a symmetric real matrix with only integer...

Homework Statement A car is rolling to the right and you try to slow it down by pushing on it to the left. You are doing A) positive work B) negative work C) no work until the car comes to a stop D) You can’t tell because I didn’t tell you which way was positive. Homework Equations...

Homework Statement http://www.screencast.com/users/trinhn812/folders/Jing/media/8fe997e1-46e5-4033-a246-fbad0acb7162 Homework Equations The Attempt at a Solution I understand that in question 25, the conductor becomes polarized and its negative charges will be more attracted...

I know that we can square an inequality if both sides are positive. But can we cube an inequality provided both the sides are positive? If no then why?

QUESTION 1 Homework Statement Two positive charges, each with Q = +10 µC, are fixed to the x-axis at x = +a and x = -a, where a = 4 m. (a) Find the electric potential at point A on the y-axis where (xA, yA) = (0, b) and b = 5 m. Take the zero of potential to be at infinity. (b) A...

If we require that the north is positive number,For example +10Km,South for the negative number,For example -10Km,So, what is the number of 10 km east then? I think there are other neither positive nor negative，Not only 0 is neither positive nor negative . Therefore, a number of absolute...

Homework Statement Find the least positive rest in division of 7^35 with 5 Homework Equations (7^35)/5 The Attempt at a Solution 7^35=378818692265664781682717625943 => 378818692265664781682717625943/5... Uhhhhh this is not the way I am supposed to take right? :cry:

Reading some QFT in which we are faced with inhomogeneous equation (\partial^\mu \partial_\mu + m^2)\phi(x)=J(x) The solution is given as \phi(x)=\phi^{(+)}_{in}(x)+\phi^{(-)}_{out}(x)+i\int{d^4 x\Delta(x-x')J(x') where \Delta is the appropriate Green's function. "in" means the...

I accept that the entropy (Shannon's) of a sum of positive numbers is the sum of the -P_n * LOG(P_n) for each number in the sum of numbers where P_n is the average contribution of a term. IE, if T = A + B, then S = -(A/T)*LOG(A/T) - (B/T)*LOG(B/T). But what about the entropy of A*B...

I explained to my class that in projectile motion one always chooses the positive time answer with the negative time answer being dropped. Then a student asked if two positive time answers were possible. I just looked at it assuming that t+/- are both positive and got the result that for t+ to...

Show that every positive integer is a sum of one or more numbers of the form 2^r3^s, where r and s are nonnegative integers and no summand divides another. not my doubt just found it interesting so posted here :smile:

Isn't it true that if a function f(t) satisfies f'(t) > 0 on some interval, then f is STRICTLY increasing on that interval; i.e., that s < t implies that f(s) < f(t)?

Hi If you are kind enough to answer this please bear in mind that I know next to no physics and I'm quite intimidated by the subject so please don't give me an intractable answer that I won't understand. Please feel free to answer as if you are talking to a nice but dim high school student...

Hi (I'm not sure where this question belongs) I had a general question about hamiltonians, do they need to be positive definite? is this required in QM, or is this a relativistic requirement? cheers M

does the following inequality holds for every POSITIVE 'x' ? e^{-x}-1\le Cx^{1/4+e} here 'C' and e are positive constants i think that for very very small 'e' the constant must be very BIG but no other hint i find

Consider a positive charge +q placed at the origin. Let A and b be two points in the space with position vectors rA and rB respectively. What will be the work done by an external force equal and opposite to the Coulumbic force, in moving a unit positive charge from A to B, irrespctive of the...

A problem asks to find all possible pairs (x, y) of positive integers that satisfy the equation: x3 = y2 – 15 There are 2 pairs (so far) that satisfy the equation: x = 1, y = 4 x = 109, y = 1138 It's possible that these 2 points are the only two positive integer solutions...

I've achieved positive magnetoresistance (MR) in CNT composite thin films with a small percentage of Fe in it. Fe injects spin polarized electrons into CNT. But +ve MR means that resistance is increasing with magnetic field. But due to injection of spin polarized electrons the current has to...

Homework Statement How much energy is need to place four positive charges, each of magnitude +5.0 mC, at the vertices of a square of side 2.5 cm? Homework Equations E = kQ/r^2 The Attempt at a Solution I'm really not sure if what I did is close to correct, but I got an answer...

I have a feeling that for any n x n non-trivial matrix A, trace(A*A) is always positive. Is it true?

sorry for the many threads Let S_n denote the number of ways of expressing n as positive integrs.. S_1=1 , s_2=2, s_3=4 .. Prove that S_n=S_{n-1}+S_{n-2} ---S_1+1 no idea to prove that :

I can't understand how does the absence of an electron at a point creates a positive charge there. In my opinion, it is wrong on account of conservation of charge. Because if we consider an electron(at a point A) as a system, and if the electron get displaced to another point B(in the system)...

Homework Statement Prove that T is positive definite if and only if \sum_{i,j} A_{ij}a_{j}\bar{a_{i}} > 0 for any non-zero tuple (a1, ...... , an ) Let A be [ T ]_{\beta} where \beta is an orthogonal basis for T The Attempt at a Solution the sum looked like the matrix...

For all positive real numbers x,y prove that: \frac{1}{1+\sqrt{x}}+\frac{1}{1+\sqrt{y}} \geq \frac{2\sqrt{2}}{1+\sqrt{2}}

Find the number of positive integers in the range of 1976 through 3776 that are not divisible by 17. A={\mathbb{Z}^+\ \mbox{not divisible by 17}} Then I am looking for A^c I am not sure how to do this though.

How can we prove that spring constant is always positive??

Ok, so I have this Expression, (6x+2 x 42x-4 x 35-x x 2x-6)/(124x+3 x 92x-3) But it needs to be simplifyed, and expressed with positive indices. Now as far as my knowledge takes me, this can't be simplifyed, but then I am probably wrong. If anybody could help to solve, that would be great.

Simplify and express with positive indices, a little help? I am no good at these, can anyone show me how to work these out? (18x3 X 2x-4)/(4x-5 X 6x) 83sqrt(p12 q-8) X 34sqrt(p-10 q9) and (6x+2 X 42x-4 X 35-x X 2x-6)/(124x+3 X 92x-3) ps. The Capital X's are multiplication signs

Hello, I'm thinking of some alternative ways of accelerating particles. I know that it's quite common to have accelerated particles pass along a positively charged foil which strips the electrons of the particles and reverses the particle's polarity. Is there a way to do the opposite? I.e...

As my title says, I need to take only the positive square root of some evaluation. For my calculation, the negative square root is extraneous. What I do is a normalization of a wave function: J = Integrate[Psi[x]^2, {x, 0, a}] sol = Solve[J == 1, A] A /. sol My only problem is those...

Homework Statement Find the range of the number k so that the equation 100^x-10^(x+1)+k=0 has two distinct positive roots Homework Equations The Attempt at a Solution I know if it says for two distinct roots only , k<25 but now its two distinct POSITIVE roots , so how ?

Can someone tell me what this actually is. So, in the case when the Hessian is positive (or negative) semidefinite, the second derivative test is inconclusive. However, I think I've read that even in the case where the Hessian is positive semidefinite at a stationary point x, we can still...

Hi, I have the following question. What is: A. Positive accelaration. B. Negative accelaration. C. Positive decelaration. D. Negative decelaration. If I am not wrong then: A is just getting faster. B is getting slower(Not sure about that) C is just getting slower. D is going...

These questions, being so basic, were harder to find answers to on the forums (or elsewhere). At least, it was harder to find an answer that satisfied my curiosity. I need a DEEPER, simpler, and more logical understanding of these concepts.: What does it mean for a particle to have a positive or...

Homework Statement Prove that there is no smallest positive irrational number Homework Equations The Attempt at a Solution I have no idea how to do this, please help walk me through it.

Homework Statement A cruise ship leaving port, travels 50.0 km 45.0 degrees north of west and then 70.0 km 30 degrees north of east. Find a. The ship's displacement vector (the answer is Rx=25.3 km, Ry=70.4) b. The displacement vector's magnitude and direction...

Homework Statement Suppose that if k is a measurable function and {x : k(x) > 0} has a positive measure, then {x : k(x) >= p} has positive measure for some p > 0 Homework Equations Lebesgue measureThe Attempt at a Solution What is positive measure? is it just another word for measurable? Can I...

Homework Statement For each positive integer n, let T(n) be the number of triangles with integer side lengths, positive area, and perimeter n. For example, T(6) = 1 since the only such triangle with a perimeter of 6 has side lengths 2, 2 and 2. (a) Determine the values of T(10), T(11) and...

Homework Statement I'm looking at a problem where we have to draw the field lines above between and below two parallel planes going to infinity. Separated by distance D, both having equal positive surface charge density. 2. The attempt at a solution I know that there will be perpendicular...

1. Suppose v_1, v_2, . . . v_k are non-zero vectors is R^n such that (v_i,v_j)<= 0 for all i,j. Determine, with proof, the maximal possible k for n = 3, and also for arbitrary n. 2. A is 2x2, A(1,1)=A(2,2)=x-1, A(1,2)=1, A(2,1)=0. Find invertible P,Q such that P*A*Q is diagonal. I tried...

hello, if i have a sequence of definite positive matrices that converges, is it always that the limit matrix is always a definite positive matrix? if it's true, can someone please tell me why or link me to some proof? thank you.

Hello; Is this statement true? A hydrogen positive ion would have no electrons, and pure hydrogen itself has no neutrons. Therefore, would it simply be a proton? Thanks.

Hi everyone, This is related to my previous https://www.physicsforums.com/showthread.php?t=392069" Let A=(a_{ij}) be a symmetric (i.e., over reals) PSD matrix with the following conditions on Leading Principle Minors (determinant of the submatrix consisting of first i rows and i...

Hi everyone, Let A=(a_{ij}) be a symmetric (i.e., over reals) PSD matrix. Then is the following correct? "If any principle minor ( \ne A ) be zero, then all principle minor contained in this minor should also be zero". I can not prove or disprove it..any help? By the way how...