SOLUTION: A is a 3x3 matrix A= [a, 3, 4] [a, -3, 8] [8, 4, a] find all values of |A|=0.

Algebra ->  Matrices-and-determiminant -> SOLUTION: A is a 3x3 matrix A= [a, 3, 4] [a, -3, 8] [8, 4, a] find all values of |A|=0.      Log On


   

Question 612687: A is a 3x3 matrix
A= [a, 3, 4]
[a, -3, 8]
[8, 4, a]
find all values of |A|=0.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
A is a 3x3 matrix
A=
[a, 3, 4]
[a, -3, 8]
[8, 4, a]
find all values of |A|=0.
--------------
Equation:
-3a^2 +16a + 192 - (-96+32a+3a^2) = 0
----
-3a^2-3a^2 + 16a - 32a + 96 +192 = 0
-6a^2 - 16a + 288 = 0
-----
3a^2 + 8a - 144 = 0
a = 5.722 or x = -8.389
====
Cheers,
Stan H.