SOLUTION: How do you find the value of |A| in this problem, A = [ -1 4, 9 -3] 2x2 matrix???

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Question 1053542: How do you find the value of |A| in this problem, A = [ -1 4, 9 -3] 2x2 matrix???
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
A is a matrix. The notation abs%28A%29 means "The determinant of matrix A"

So let's find the determinant of this matrix

Solved by pluggable solver: Finding the Determinant of a 2x2 Matrix

If you have the general 2x2 matrix:

%28matrix%282%2C2%2Ca%2Cb%2Cc%2Cd%29%29

the determinant is: D=a%2Ad-c%2Ab

So this means that

abs%28matrix%282%2C2%2Ca%2Cb%2Cc%2Cd%29%29=a%2Ad-c%2Ab

Note: the vertical bars denote a determinant.


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So in this case the determinant of %28matrix%282%2C2%2C-1%2C4%2C9%2C-3%29%29 is:


abs%28matrix%282%2C2%2C-1%2C4%2C9%2C-3%29%29=%28-1%29%28-3%29-%289%29%284%29=3-36=-33


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Answer:

So abs%28matrix%282%2C2%2C-1%2C4%2C9%2C-3%29%29=-33 which means that the determinant of the matrix %28matrix%282%2C2%2C-1%2C4%2C9%2C-3%29%29 is -33