evaluate the following determinant by expanding according to co factors of:

(a) the third row
(b)the second column

1)
|2 -1 2|
|1 0 3 |
| 0 2 1 |

Question

evaluate the following determinant  by  expanding according to co factors of:

(a) the third row
(b)the second column

1)
     |2  -1  2|
     |1   0  3 |
     | 0  2  1 |

anonymous · Answer

i got the answer 7 when i did it but the answers is -7

anonymous · Answer

(a) 0(-1*3-0*2)-2*(2*3-(2*1)+1(2*0-(-1))=-8+1=-7

anonymous · Answer

oh i see

anonymous · Answer

does the sign change if there is a negative in front or does it remain +-+

anonymous · Answer

(b) -(-1)*(1*1-0*3) +0*(2*1-0*2)-2(2*3-1*2)=+1-8=-7

anonymous · Answer

+ -+
-+-
+-+
this is how u open, wen there a negative sign in the number the sign automatically gets changed to + or - , if ur multiplying it by - or +. d'u get it ?

anonymous · Answer

yes thank you for clarifying :)