Hello, could I please receive some assistance in the solving of the following homework problem. My answer does not math the book's. Thanks! Here it is...

Evaluate the determinant of the following 4 by 4 matrix

2 1 2 1

3 0 1 1

-1 2 -2 1

-3 2 3 1

Book's answer: 20 (How?)

My answer: -23