Form 8767: #17, #18 and #35
Posted: Mon Aug 29, 2011 2:22 am
#17
Let * be the binary operation on the rational numbers given by a * b = a + b + 2ab, which of the following are true?
I: * is commutative
II: There is a rational number that is a *-indentity
III: Every rational number has a *-inverse
The answer is C: I and II.
Obviously, * is commuatative, but I have problem finding the indentity. Can anyone show me?
#18
A group G in which (ab)^2 and a^2 b^2 for all a, b in G is necessarily
(A) finite
(B) cyclic
(C) of order two
(D) abelian
(E) none of the above.
The answer is D.
Can anyone explain this to me?
#35
The rank of the matrix is?
| 1 2 3 4 5 |
| 6 7 8 9 10|
| 11 12 13 14 15|
| 16 17 18 19 20|
| 21 22 23 24 25|
The answer is 2.
Can anyone show me?
Let * be the binary operation on the rational numbers given by a * b = a + b + 2ab, which of the following are true?
I: * is commutative
II: There is a rational number that is a *-indentity
III: Every rational number has a *-inverse
The answer is C: I and II.
Obviously, * is commuatative, but I have problem finding the indentity. Can anyone show me?
#18
A group G in which (ab)^2 and a^2 b^2 for all a, b in G is necessarily
(A) finite
(B) cyclic
(C) of order two
(D) abelian
(E) none of the above.
The answer is D.
Can anyone explain this to me?
#35
The rank of the matrix is?
| 1 2 3 4 5 |
| 6 7 8 9 10|
| 11 12 13 14 15|
| 16 17 18 19 20|
| 21 22 23 24 25|
The answer is 2.
Can anyone show me?