Find the determinant

Question

|1 -1 3|

|-1 2 -2|

|2 -2 4|

Answer 1

Hi Zandalee,

 

To find the determinant of a 3 x 3 matrix . . . 

 

a   b   c

d   e   f

g   h   i

 

a(ei - fh) - b(di - fg) + c(dh - eg)

 

It looks really crazy, I know, but once you know the formula, you just substitute . . . very carefully!

 

1[(2*4) - (-2 * -2)] - -1[(-1 * 4) - (-2 * 2)] + 3[(-1 * -2) - (2 * 2)]

1(8-4) - -1[-4 - (-4)] + 3(2 - 4)

1(4) - -1(0) +3(-2)

4 + 0 - 6 = -2