- Tue Oct 05, 2010 3:34 pm
- Forum: Matrix (Linear) Algebra
- Topic: Proof:Show that BAB^-1 is invertible
- Replies:
**1** - Views:
**3321**

Let A and B be any invertible matrix. Show that the matrix BAB^-1 is invertible. What is its inverse?

- Mon Apr 19, 2010 9:59 pm
- Forum: Calculus
- Topic: Optimization Problem: Rain Gutter
- Replies:
**1** - Views:
**3166**

Hey there Purplemath! I need some help setting up the problem: A rain gutter is to be constructed from a long 30 cm wide sheet of metal by bending two sides upwards at and angle of theta so that each of the sides and bottom is 10 cm wide. Determine the angle theta so that the cross-sectional area of...

- Wed Mar 17, 2010 11:00 pm
- Forum: Calculus
- Topic: Related Rates: A plane, 40 mi from airport, is flying at
- Replies:
**2** - Views:
**2895**

Thank you, this helped greatly.

- Wed Mar 17, 2010 8:16 am
- Forum: Calculus
- Topic: Related Rates: A plane, 40 mi from airport, is flying at
- Replies:
**2** - Views:
**2895**

Need some help setting up the following problem:

A plane is 40 miles (horizontally away from an airport) flying at a constant altitude of 4 miles. The radar at the airport determines that the distance from the plane to the radar dish is changing at 240 mph. Determine the speed of the plane.

A plane is 40 miles (horizontally away from an airport) flying at a constant altitude of 4 miles. The radar at the airport determines that the distance from the plane to the radar dish is changing at 240 mph. Determine the speed of the plane.

- Sun Mar 29, 2009 2:07 am
- Forum: Beginning Algebra
- Topic: Need help with Complex Fraction
- Replies:
**3** - Views:
**2634**

Thanks for the quick reply!!! I think the reason I was confused with factoring the denominator is because my book does not refer to the rational roots test in prior sections, so I would never had known how to factor it anyway. Thus far it has only demonstrated factoring by common monomial, special p...

- Sat Mar 28, 2009 10:28 pm
- Forum: Beginning Algebra
- Topic: Need help with Complex Fraction
- Replies:
**3** - Views:
**2634**

Help me finish this problem....Cant factor by grouping, what other method?