1.

Write minros and cofactros of the elements of the determinants: (i) `|{:(1,0,4),(3,5,-1),(0,1,2):}|`

Answer» (i) `Let A=|{:(1,0,0),(0,1,0),(0,0,1):}|`
Minors `M_(11)=|{:(1,0),(0,1):}|=1-0=1`
`M_(12)=|{:(0,0),(0,1):}|=0-0=0,M_(13)=|{:(0,1),(0,0):}|=0-0=0`
`M_(21)=|{:(0,0),(0,1):}|=0-0=0,M_(22)=|{:(1,0),(0,1):}|=1-0=0,`
`M_(23)=|{:(1,0),(0,0):}|=0-0=0`
`M_(33)=|{:(1,0),(0,1):}|=1-0=1
Cofactors`
`A_(11)=(-1)^(1+1)M_(11)=1,A_(12)=(-1)^(1+2)M_(12)=0`
`A_(13)=(-1)^(1+3)M_(13)=0`
`A_(21)=(-1)^(2+1)M_(21)=0,A_(22)=(-1)^(2+2)M_(22)=1`
`A_(23)=(-1)^(2+3)M_(23)=0`
`A_(31)=(-1)^(3+1)M_(31)=0,A_(32)=(-1)^(3+2)M_(32)=0`,
`A_(33)=(-1)^(3+3)M_(33)=1`
`Let A= |{:(1,0,4),(3,5,-1),(0,1,2):}|`
Minors `=|{:(5,-1),(1,2):}|=10+1=11,`
`M_(12)=|{:(3,-1),(0,2):}|=6-0=6, M_(13)=|{:(3,5),(0,1):}|=3-0=3`
`M_(23)=|{:(1,0),(0,1):}|=1-0=1`
`M_(31)=|{:(0,4),(5,-1):}|=0-20-=-20`
`M_(32)=|{:(1,4),(3,-1):}|=-1-12=-13`,
`M_(33)=|{:(1,0),(3,5):}|=5-0=5`
Cofactors `A_(11)=(-1)^(1+1)M_(11)=11`
`A_(12)=(-1)^(2+1)M_(21)=4,A_(22)=(-1)^(2+2)M_(22)=2`,
`A_(23)(-1)^(3+1)M_(31)=-20,A_(32)=(-1)^(3+2)M_(32)=13,`
`A_(33)=(-1)^(3+3)M_(33)=5`


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