What are the values of a that make A=0?

Thread starter ~Sam~
Start date Oct 18, 2009

AI Thread Summary

To determine the values of 'a' that make the determinant of matrix A equal to zero, cofactor expansion is suggested as the method of approach. The matrix A is given as a 3x3 matrix with variable 'a' in multiple positions. Participants express confusion about how to apply cofactor expansion effectively in this scenario. The discussion emphasizes the need for clarity in the calculations involved in finding the determinant. Ultimately, the goal is to identify all values of 'a' that satisfy the condition A=0.

Oct 18, 2009

~Sam~

Homework Statement

if
A=
a 3 5
a -7 6
5 4 a

find all values of a that make A=0. Give your answer as a comma-separated list.

Homework Equations

Looks like the cofactor expansion would be used

The Attempt at a Solution

I'm really lost in this one.

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Oct 18, 2009

Hurkyl

Staff Emeritus

Science Advisor

Gold Member

~Sam~ said:

Looks like the cofactor expansion would be used

What did you get by using it?

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