Solving Matrix A: Find All Values of a

[losmets90]

Given the matrix
A= [a 1 9]
[a -6 3]
[5 -8 a]

find all values of a that makes

give your answers in increasing order.
a can be _ & _

NEED HELP! IM BEYOND STUCK! I have no idea to even approach this problem! Thanks!

 

[netheril96]

I don't understand why you are stuck.
You don't know how to calculate determinants or solve equations?

 

[losmets90]

I don't know how to solve the equation

 

[netheril96]

\[<br /> \left| {\left. {\bf{A}} \right|} \right. = 285 - 48a - 7a^2 = 0<br /> \]<br />
You can't solve that?

 

[losmets90]

oh, now I feel dumb. Thanks for the help!