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Type: Posts; User: mcwang719

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1. ## Thread: Distance, Velocity, and Acceleration of a vehicle

by mcwang719
Replies
6
Views
2,422

### ok. so are a and b correct? I was thinking if I...

ok. so are a and b correct? I was thinking if I plugged in t=3 into the first equation to get u. then put that value into 3.6-0.06u=a.

So u= (3.6/.06)(1-e^(-.06*3))+45e^(-0.06*3)) to get...
2. ## Thread: Distance, Velocity, and Acceleration of a vehicle

by mcwang719
Replies
6
Views
2,422

### sorry i messed up on the math. I did it again and...

sorry i messed up on the math. I did it again and got t=18.31 as well. So are my other steps correct I know now that I have to plug in 18.31 instead of 1.78, so if I make those corrections will the...
3. ## Thread: Distance, Velocity, and Acceleration of a vehicle

by mcwang719
Replies
6
Views
2,422

### b) used the first equation. and plugged in the...

b) used the first equation. and plugged in the numbers 55= (3.6/.06)(1-e^(-0.6t) +45e^(-.06t) and got t=1.78 seconds

Then used the answer to to get a) plugged t into equation 2....
4. ## Thread: Distance, Velocity, and Acceleration of a vehicle

by mcwang719
Replies
6
Views
2,422

### Distance, Velocity, and Acceleration of a vehicle

The acceleration of a vehicle takes the form du/dt =3.6 - 0.06u where u is the vehicle speed in ft/sec. The vehicle is traveling at 45 ft/sec at time T.

a) Determine the distance traveled by the...

by mcwang719
Replies
6
Views
1,364

### Can you explain this to me I know R X R is the...

Can you explain this to me I know R X R is the cartesian product, but I'm having trouble applying it to this problem

by mcwang719
Replies
6
Views
1,364

### Equivalence relations

For the following relation indicate whether it's reflexive, symmetric, or transitive?
R, where (x,y)R (z,w) iff x+z less or equal to y+w, on the set real numbers X real numbers.

Looking at this...
7. ## Thread: Clarification on a proof: ...Prove m=b iff a|b

by mcwang719
Replies
1
Views
1,306

### Clarification on a proof: ...Prove m=b iff a|b

Hi I'm working on a proof I have the solution but don't understand it fully. The problem is:

Let a and b be natural numbers and LCM(a,b)=m. Prove that m=b if and only if a divides b.
Proof:...
8. ## Thread: Let H = {x in group G | x^2 = e}. Prove or disprove that....

by mcwang719
Replies
13
Views
3,590

### Thank you very much Daon I really appreciate it!...

Thank you very much Daon I really appreciate it! You have been extremely helpful!
9. ## Thread: Let H = {x in group G | x^2 = e}. Prove or disprove that....

by mcwang719
Replies
13
Views
3,590

### Yes you need commutativity of H to be a group. So...

Yes you need commutativity of H to be a group. So if G is non-abelian than, than H is not a subgroup?
10. ## Thread: Let H = {x in group G | x^2 = e}. Prove or disprove that....

by mcwang719
Replies
13
Views
3,590

### There are two parts to this question. Prove or...

There are two parts to this question. Prove or Disprove:
a) H is a subgroup of G
b) If G is abelian, H is a subgroup of G

I'm a little confused, so I just proved a) and how is proving b) any...
11. ## Thread: Let H = {x in group G | x^2 = e}. Prove or disprove that....

by mcwang719
Replies
13
Views
3,590

### Sorry let me rephrase that. What I got from the...

Sorry let me rephrase that. What I got from the book is we assume a and b belong to H. This means a^2=e and b^2=e and we must show that (ab^-1)=e.

So (ab^-1)^2= ab^-1ab^-1= a^2(b^-1)^2=...
12. ## Thread: Show H is equal or less than N(H).

by mcwang719
Replies
3
Views
887

### Thanks Pka! That helped out a lot. Can you give...

Thanks Pka! That helped out a lot. Can you give me some pointers to show H is equal or less than N(H).
13. ## Thread: Let H = {x in group G | x^2 = e}. Prove or disprove that....

by mcwang719
Replies
13
Views
3,590

### so can we say a^2=e and b^2=e so (ab^-1)=e. So...

so can we say a^2=e and b^2=e so (ab^-1)=e. So (ab^-1)^2= ab^-1ab^-1= a^2(b^-1)^2= (a^2)(b^2)^-1= ee^-1= ab^-1.
14. ## Thread: Show H is equal or less than N(H).

by mcwang719
Replies
3
Views
887

### Show H is equal or less than N(H).

Let G be a group and let H be a subgroup of G.

N(H)={x belongs G / xHx^-1 = H}
a)Show that H is equal or less than N(H).
b) Prove that N(H) is a subgroup of G.

To be honest I'm completely...
15. ## Thread: Determine whether or not U(14) is cyclic.

by mcwang719
Replies
11
Views
2,786

### Ok after reading the book I finally think I got...

Ok after reading the book I finally think I got it! U(14) is cyclic because it has the generators <3> and <5>.
<3>={1,3,9,13,11,5} (has all the elements)
<5>={1,5,11,13,9,3}
<9>={1,9,11} (doesn't...
16. ## Thread: Determine whether or not U(14) is cyclic.

by mcwang719
Replies
11
Views
2,786

### What I did was I followed your example on U(6),...

What I did was I followed your example on U(6), so in U(14), 13^0=1, 13^1=13 and so on. Isn't that what you showed in your example with U(6)? Thanks.
17. ## Thread: Determine whether or not U(14) is cyclic.

by mcwang719
Replies
11
Views
2,786

### Ok so I think I understand U(14) is cyclic...

Ok so I think I understand U(14) is cyclic because U(14)=<13>={13^0,13^1,13^2...}={1,13}=U(14). Is that correct? thanks
18. ## Thread: Determine whether or not U(14) is cyclic.

by mcwang719
Replies
11
Views
2,786

### So all the elements raised to the 6th power gives...

So all the elements raised to the 6th power gives the identity. Is that what you mean?
19. ## Thread: Determine whether or not U(14) is cyclic.

by mcwang719
Replies
11
Views
2,786

### So could I say U(14) is cyclic because 1*3 mod...

So could I say U(14) is cyclic because 1*3 mod 14=3, 3*5 mod 14=1, 5*9 mod14=3, 9*11 mod 14=1, 11*13 mod 14=3? Would this be enough to show that it's cyclic? Thanks.
20. ## Thread: Determine whether or not U(14) is cyclic.

by mcwang719
Replies
11
Views
2,786

### Determine whether or not U(14) is cyclic.

I'm having some trouble with this problem. So U(14) = {1, 3, 5, 9, 11, 13}. Do I simplify need to find a generator? (If there is a...
21. ## Thread: How does (beta)(beta)^(-1) equal 2(beta)?

by mcwang719
Replies
4
Views
725

### Thanks unco!!! you've been very helpful.

Thanks unco!!! you've been very helpful.
22. ## Thread: How does (beta)(beta)^(-1) equal 2(beta)?

by mcwang719
Replies
4
Views
725

### it doesn't state that it equals 2(beta) i kinda...

it doesn't state that it equals 2(beta) i kinda assumed because (beta)(beta)^-1= 2m right??
23. ## Thread: How does (beta)(beta)^(-1) equal 2(beta)?

by mcwang719
Replies
4
Views
725

### How does (beta)(beta)^(-1) equal 2(beta)?

Hello this problem is from my modern algebra class.

Let (alpha) and (beta) belong to S(sub n). Prove that (beta)(alpha)(beta)^-1 and (alpha) are both even or both odd.

24. ## Thread: Given elts of the group SL(2,R), find |A|, |B|, and |AB|.

by mcwang719
Replies
11
Views
2,236

### i got it!!!! i reread you're last paragraph and...

i got it!!!! i reread you're last paragraph and finally got it A^4= identity. yay!!!! thanks everyone.
25. ## Thread: Given elts of the group SL(2,R), find |A|, |B|, and |AB|.

by mcwang719
Replies
11
Views
2,236

### Can you explain how |A|=4? Thanks!

Can you explain how |A|=4? Thanks!
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