1.

The system of equations x+y+z=5, x+2y+lamdaz=mu, x+2y+3z=9 has (i) unique solution of lamda!=3 (ii) infinitely many solutions if lamda=3, mu=9 (iii) no solution if lamda=3, mu!=9 From the above statements, number of correct statements is

Answer»

1
2
3
0

Solution :The system of equations
`x+y+z=5`
`x+2y+lamdaz=mu,x+2y+3z=9` is EQUIVALENT of `AX=B`,
where
`A=[(1,1,1),(1,2,lamda),(1,2,3)],X=[(x),(y),(z)],B=[(5),(mu),(9)]`
Augmented matrix
`[A|B]=[(1,1,1),(1,2,lamda),(1,2,3)][(5),(mu),(9)]`
`=[(1,1,1),(0,1,lamda-1),(0,1,2)][(5),(mu-5),(4)]`
`{:((R_(2)toR_(2)-R_(1)),(R_(3)toR_(3)-R_(1))):}`
`=[(1,1,1),(0,1,lamda-1),(0,0,3-lamda)][(5),(mu-5),(9-mu)]`
`:.` Rank A=` rank `[A|B]` if lamda!=3`,
`:.` The system has UNIQUE solution
if `lamda!=3`
`:.` (i) is correct
if `lamda=3,mu=9,` rand `A=` rank `[A|B]=2`
`lt` number of unknowns.
`:.` The sytem has infinitely many solutions if
`lamda=3,mu=9`
If `lamda=3, mu!=9`
rank `A=2`,
rank `[A|B]=3`
`:.` The system has no solution.


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