Question -
Answer -
The given determinant is
.
We have:
M21┬а=┬а
тИ┤A21┬а= cofactor of┬аa21┬а=(тИТ1)2+1┬аM21┬а= 7
M22┬а=┬а
тИ┤A22┬а= cofactor of┬аa22┬а=(тИТ1)2+2┬аM22┬а= 7
M23┬а=
тИ┤A23┬а= cofactor of┬аa23┬а=(тИТ1)2+3┬аM23┬а= тИТ7
We know that ╬Ф is equal to the sum of theproduct of the elements of the second row with their corresponding cofactors.
тИ┤╬Ф =┬аa21A21┬а+┬аa22A22┬а+┬аa23A23┬а=2(7) + 0(7) + 1(тИТ7) = 14 тИТ 7 = 7