2x+9y+5z=8 . . . (i) 2x+3y−z=−4 . . . (ii) x−2z=−5 . . . (iii) On subtracting Eq. (ii) from Eq. (i), we get y+z=2 ⇒‌‌y=2−z ⇒‌‌x=2z−5 If ‌‌z=ct ⇒‌‌y=2−ct and x=2ct−5 x=−5+at=2ct−5 ⇒‌‌a=2c y=2+bt=2−ct b=−c a,b,c≡(2c,−c,c) If c=1⇒(a,b,c)≡(2,−1,1)