If x=a,  y=b,  z=cis a solution of the system of linear equations x+8y+7z=0,  9x+2y+3z=0,  x+y+z=0such that the point (a,b,c)lies on the plane x+2y+z=6 then 2a+b+c=

a+8b+7c=0      9a+2b+3c=0,   a+b+c=07b+6c=0,     7a+c=0b=−6c7,        a=−c7(a,b,c)lies on the plane x+2y+z=6⇒a+2b+c=6⇒−c7−12c7+c=6⇒c=−7,     b=6,    a=1∴ 2a+b+c=  2+6−7=1