# Recent content by knowLittle

1. ### Prove Set of all onto mappings from A->A is closed

Still not very sure on how to start. BTW, is there anything rescuable from my first approach?
2. ### Prove Set of all onto mappings from A->A is closed

Thanks. We need to show that ##fog## is onto or in other words fog = z = f(g(x)) =A? f: A-> A : f(a) = A g: A ->A: g(a) = A Is this correct?
3. ### Prove Set of all onto mappings from A->A is closed

Homework Statement Prove that set of all onto mappings of A->A is closed under composition of mappings: Homework Equations Definition of onto and closure on sets. The Attempt at a Solution Say, ##f## and ##g## are onto mappings from A to A. Now, say I have a set S(A) = {all onto mappings of A...
4. ### Show that is not onto (##\frac{x}{x^2+1}##)

Once, I have ##y(x^2+1) = x## what else can I do? ## y x^2 + y = x## divide all over x^2 wouldn't work.
5. ### Show that is not onto (##\frac{x}{x^2+1}##)

The question says that A= R-{0} and B =R. Then, that f:A ->B and I need to show whether they 1-1 and whether they are onto. Prove. Thanks for the hint.
6. ### Show that is not onto (##\frac{x}{x^2+1}##)

Homework Statement I need to show that $$\frac{x}{x^2+1}$$ is either onto or not. My domain is $$R-{0}$$ and range is $$R$$ Homework Equations I have learn to do this to show that a function is surjective y = $$\frac{x}{x^2+1}$$ and solve for x, but I am not sure how to proceed here. The...
7. ### Bohr-Sommerfeld Rule

Homework Statement Imagine that force for is atom was ## F= - \frac{\beta}{r^4}##, rather than ##F=- \frac{ke^2}{r^2}##, and consider only circular orbits, it would remain true that ##L_n= n \hbar## a.) From Netwon's law find the relationship between ##T ##(Kinetic Energy) and ##V##, b.) Find...
8. ### Ambiguous GRE Question?

Thank you, I understand now.
9. ### Ambiguous GRE Question?

Homework Statement Title of pie chart: New Construction in Daisy Hill Subdivision Given a pie chart with sections: Currently Completed: 26% Currently Under Construction: 42% Approved, but Not Yet Started: 32% Question: When construction is completed in Daisy Hill Subdivision there'll...
10. ### Classical Relativity and the Speed of Light

Homework Statement Let's assume that the classical ideas of space and time are correct, so that there could only be one frame, "ether", in which light traveled with same speed in all directions. Assume that the earth's speed relative to the ether frame is our orbital speed around the sun...
11. ### Relativity of Orientation & Origin

Ok, thank you. I remember things better now. ## F_{net} = m*a ## ## F_x = m*g*sin(\theta)## ## F_{\mu} = \mu * F_N## ##F_{net}= F_x- F_{\mu}=m*a## ## a = g(sin(\theta) - \mu(cos(\theta)))## Finally, ## S(t)= (1/2)g(sin(\theta) - \mu(cos(\theta)))* t^2 ##
12. ### Relativity of Orientation & Origin

Homework Statement At time t=0, a block is released from point O on the slope shown in the figure. The block accelerates down the slope, overcoming sliding friction. a.) Choose axes 0xy as shown, and solve the equation ##\Sigma F = m a## into its x and y components. Hence find the block's...
13. ### Final Undergraduate Semester Guidance

I agree micromass, I never chose mediocre classes before for a GPA boost and I have never dropped a class. But, I thought that since the end of the undergraduate program is near and there are requirements for graduate school, I should make an exception. Austrian, the classes are Theory of...
14. ### Final Undergraduate Semester Guidance

Hello all, I have a bit of a dilemma. I have two free electives to take and I am considering taking two "advanced" math classes and get a math minor or two semi-good classes from whatever. If I take two math classes and I get A's, it would be lovely. But, If I get low grades, my GPA will...
15. ### Prove Divisibility

I like LaTEX. Why do you hate it?