- Mon Jun 29, 2009 5:04 pm
- Forum: Matrix (Linear) Algebra
- Topic: given system, find solns, show solns form vector space, and
- Replies:
**1** - Views:
**3435**

I need to find the set of solutions to a system of linear equations, show that they are a vector space of R^4, and find a basis for them. The equations are: x 1 - 2x 3 - 3x 4 = 0 x 2 - 3x 3 + x 4 = 0 2x 1 - x 2 - x 3 - 7x 4 = 0 I got a solution of x = x 3 *(2, 3, 1, 0). I could show closure, but how...

- Mon May 18, 2009 8:11 pm
- Forum: Discrete Math
- Topic: need to find the median from frequency table??
- Replies:
**1** - Views:
**3240**

There are 2+3+7+5+3=20 points, so the median is the average of the 10th & 11th. But you have classes, not the actual points, so you have to start at the bottom of the interval (10-14, probably 9.5). The 10th point is 5th (of 7) in the interval & the interval is 5 wide, so its 9.5+(5/7)(5).

- Wed Mar 25, 2009 7:46 pm
- Forum: Matrix (Linear) Algebra
- Topic: A, B, and C are 2 x 2 matrices. Solve eqn for C: B=(BC+2A)
- Replies:
**1** - Views:
**3038**

My quess is this: C=inv(A)-(2A)(inv(B)), but I am not sure...that is whay I am writing you.

Thank you for your time

- Mon Mar 23, 2009 6:24 pm
- Forum: Advanced Algebra ("pre-calculus")
- Topic: value of sqrt(2sqrt(2sqrt(...))) (I'm told there's a trick?)
- Replies:
**3** - Views:
**4723**

- Sun Mar 22, 2009 4:15 pm
- Forum: Advanced Algebra ("pre-calculus")
- Topic: value of sqrt(2sqrt(2sqrt(...))) (I'm told there's a trick?)
- Replies:
**3** - Views:
**4723**

I'm trying to find the value of sqrt(2sqrt(2sqrt(...))). I figure you start by setting this equal to "x". But then what?

I'm told there's a trick to this, so maybe that's why I'm stuck?

*Edited to correct misunderstanding of original puzzle.*

I'm told there's a trick to this, so maybe that's why I'm stuck?

- Fri Mar 20, 2009 1:26 pm
- Forum: Matrix (Linear) Algebra
- Topic: find values for a, b, and c for which matrix A is symmetric
- Replies:
**1** - Views:
**8808**

find values for a, b, and c for which the matrix A is symmetric

matrix A = 2 a-2b+c 2a+b+c 3 5 a+c 0 -2 7i know that a-2b+c=3 and son on ... but i cant seem to process the equation to get answers consistent for the equation.

- Wed Mar 04, 2009 7:41 pm
- Forum: Matrix (Linear) Algebra
- Topic: Matrix A where system Ax = b solvable, but not nec. uniquely
- Replies:
**1** - Views:
**2860**

Is there a way to do this that does

- Wed Mar 04, 2009 7:35 pm
- Forum: Matrix (Linear) Algebra
- Topic: For 2-by-2 matrix A, show that det(sA) = s^2 * det(A)
- Replies:
**2** - Views:
**2942**

- Sun Mar 01, 2009 7:15 pm
- Forum: Matrix (Linear) Algebra
- Topic: For 2-by-2 matrix A, show that det(sA) = s^2 * det(A)
- Replies:
**2** - Views:
**2942**

Let A be any 2-by-2 matrix, and let s be any real-valued scalar. Show that det (sA) = s^{2}* det (A).

A = [ a b ] sA = [ sa sb ] [ c d ] [ sc sd ] det(A) = ad - cb det(sA) = (sa)(sd) - (sc)(sb) = s^2(ad) - s^2(cb) = s^2 * det(A)This seems too easy?

- Thu Feb 26, 2009 3:15 pm
- Forum: Matrix (Linear) Algebra
- Topic: prove or show false: X^2 = (identity) only if X=I or X=-I,
- Replies:
**2** - Views:
**5174**