SOLUTION: This question is from my College Algebra Class Notes and Work Guide. It deals with Cramer's Rule. {-3 4 -4} {-3 K -1} = 58 {1 4 -2} The numbers in the braquet, a

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Question 135889: This question is from my College Algebra Class Notes and Work Guide. It deals with Cramer's Rule.
{-3 4 -4}
{-3 K -1} = 58
{1 4 -2}

The numbers in the braquet, are all in one large bracket and then they all equal 58. I'm just not sure where to do with it.

Found 2 solutions by stanbon, solver91311:
Answer by stanbon(75887)   (Show Source): You can put this solution on YOUR website!
{-3 4 -4}
{-3 K -1} = 58
{1 4 -2}
--------------------
The left side is a determinant.
You are evaluate the determinant; set it equal to 58; solve for K.
---------------------
Determinant Value: [-3*K*-2+-3*4*-4 + 1*-1*4]
-[-4*K*1 + -1*4*-3 + -2*-3*4] =58
= [6K+48-4] - [-4K+12+24] = 58
= 10K+8 = 58
10K = 50
K= 5
===============
Cheers,
Stan H.

Answer by solver91311(24713)   (Show Source): You can put this solution on YOUR website!
I suspect you are supposed to solve for K.



To calculate the value of a 3X3 determinant, create a 5X3 matrix by repeating the first two columns to the left of the original 3



Next you perform the following calculation:


The three complete 3-factor diagonal products down right summed minus the three complete 3-factor diagonal products up right summed.

In your case:



You can check the arithmetic yourself, but it reduces to , but you were given that the determinant = 58, so:






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