1.

Given that the system of equations `x=cy+bz ,y=az+cx , z=bx +ay` has nonzero solutions and and at least one of the a,b,c is a proper fraction. System has solution such thatA. `x,y,z -= (1-2a^(2)):(1-2b^(2)):(1-2c^(2))`B. `x.y.z -= (1)/(1-2a^(2)):(1)/(1-2b^(2)):(1)/(1-2c^(2))`C. `x.y.z -= (a)/(1-a^(2)):(b)/(1-b^(2)):( c)/(1-c^(2))`D. `x.y.z -= sqrt(1-a^(2)):sqrt(1-b^(2)):sqrt(1-c^(2))`

Answer» Correct Answer - D
The system of equation
`-x+cy+bz=0`
`cx-y+az=0`
`bx+ay-z=0`
has a nonzero solution if
`Delta = |{:(-1,,c,,b),(c,,-1,,a),(b,,a,,-1):}|=0`
then Clearly the system has infinitely many solutions .From (1) and (2) we have
`(x)/(ac+b) =(y)/(bc+a)=(z)/(1-c^(2)) `
`" or " (x^(2))/((1-a^(2))(1-c^(2)))=(y^(2))/((1-b^(2))(1-c^(2)a)) =(z^(2))/((1-c^(2))^(2))`[From (4)]
`" or " (x^(2))/(1-a^(2))=(y^(2))/(1-b^(2)) =(z^(2))/(1-c^(2))`
from (5) we see that `1-a^(2),1-b^(2),1-c^(2)` are all positive or all negative .Given that one of a,b,c is proper fraction so
`1-a^(2) gt ,1-b^(2) gt 0,1-c^(2) gt 0` which gives `a^(2) +b^(2)+c^(2) lt 3`
using (4) and (6) we get
`1lt 3+2 abc`
`" or " abc gt -1`


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