Matrices and Determinants 4 Question 29

30. Show that the system of equations, 3xy+4z=3, x+2y3z=2 and 6x+5y+λz=3 has atleast one solution for any real number λ5. Find the set of solutions, if λ=5.

(1983,5M)

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Answer:

Correct Answer: 30. ( k=0, the given system has infinitely many solutions)

Solution:

  1. The given system of equations

3xy+4z=3x+2y3z=26x+5y+λz=3

has atleast one solution, if Δ0

Δ=|31412365λ|0

3(2λ+15)+1(λ+18)+4(512)07(λ+5)0λ5

Let z=k, then equations become

and 3xy=34kx+2y=3k2

On solving, we get

x=45k7,y=13k97,z=k



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