1.

Use matrix method to show that the following system of equation is inconsistent 3x-y+2z=3 2x+y+3z=5 x-2y-z=1

Answer» Let us take
`A=[{:(3 " "-1 "     "2),(2 "       "1 "      "3),(1 "       -2 "-1):}] , X=[{:(x),(y),(z):}] and B=[{:(3),(5),(1):}]`
The given system in matrix from is AX =B
Now  `|A|=[{:(3 " "-1 "     "2),(2 "       "1 "      "3),(1 "       -2 "-1):}]`
=3(-1+6)+1.(-2-3)+2.(-4-1)
=(15-5-10)=0
So the system will be inconsistent of |A| are
`M_(11)=5,M_(12)=-5,M_(13)=-5`
`M_(21)=5,M_(22)=-5,M_(23)=-5`
`M_(31)=-5,M_(32)=5,M_(33)=5`
So the confactors of the elements of |A| are
`A_(11)=5,A_(12)=-5,A_(13)=-5`
`A_(21)=5,A_(22)=-5,A_(23)=-5`
`A_(31)=-5,A_(32)=5,A_(33)=5`
`therefore (adjA)==[{:(5 "          "5 "        "-5),(-5 " "-5 "          "5),(-5 "       -5 "                    5):}]= =[{:(5 "   "-5 "        "-5),(5 "     "-5 "      "-5),(-5 "       5 "                      5):}]` 
`rArr (adjA)B =[{:(5 "   "-5 "        "-5),(5 "     "-5 "      "-5),(-5 "       5 "                      5):}]` `[{:(3),(5),(1):}]`
`=[{:(5.3+(-5).5+(-5).1),(5.3+(-5).5+(-5).1),((-5).3+5.5+5.1):}]=[{:(15-25-5),(15-25-5),(-15+25+5):}]`
`=[{:(-15),(-15),(15):}]neO`
Thus |A|=0and (adjA)B` ne ` O. ltbrrgt Hence the given system of equation is inconsistent


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