Q.
Let [λ] be the greatest integer less than or equal to λ. The set of all values of λ for which the system of linear equations x+y+z=4,3x+2y+5z=3, 9x+4y+(28+[λ])z=[λ] has a solution is:
D=∣∣1391241528+[λ]∣∣=−24−[λ]+15=−[λ]−9
if [λ]+9=0 then unique solution
if [λ]+9=0 then D1=D2=D3=0
so infinite solutions
Hence λ can be any red number.