SOLUTION: What is the value of the determinant? |3 6 8| |2 4 0| |3 6 8| I have absolutely not idea how to even start this problem!

Algebra ->  Matrices-and-determiminant -> SOLUTION: What is the value of the determinant? |3 6 8| |2 4 0| |3 6 8| I have absolutely not idea how to even start this problem!      Log On


   



Question 762559: What is the value of the determinant?
|3 6 8|
|2 4 0|
|3 6 8|
I have absolutely not idea how to even start this problem!

Found 2 solutions by Alan3354, MathLover1:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
What is the value of the determinant?
|3 6 8|
|2 4 0|
|3 6 8|
----------
Use minors
Using the top row:
Det = 3*minor1 - 6*minor2 + 8*minor3
---------
For minors, cross off the row & column
minor1 is
|4 0|
|6 8|
etc
------
--> 3*(4*8 - 6*0) = 96 for minor1
--> 6*(2*8 - 3*0) = -96 for minor 2
--> 8*(2*6 - 3*4) = 0 for minor3
-----
Adding those --> Det = 0
=================
Use google, wikipedia or youtube for more info

Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
|3 6 8|
|2 4 0|=
|3 6 8|
=+3%284%2A8-6%2A0%29-2%286%2A8-6%2A8%29%2B3%286%2A0-4%2A8%29
=+3%2832-6%29-2%2848-48%29%2B3%286-32%29
=+3%2826%29-2%280%29%2B3%28-26%29
=+3%2826%29-3%2826%29
=+0