[" If "a,b" and "c" are non-coplanar vectors and if "d" is such that "=(1)/(x)(a+b+c)" and "a=(1)/(3)(b+c+d)],[(1)/((1)/(x)(a+b+c+d)=)]

If a, b and c are non-coplanar vectors and if d is such that d = (1)/(x) (a + b + c) and a = (1)/(y) (b + c + d) where x and y are non-zero real numbers, then (1)/(xy) (a + b + c + d) =

If a,b and c are non-coplanar vectors, prove that 3a-7b-4c, 3a-2b+c and a+b+2c are coplanar.

If a,b and c are non-coplanar vectors, prove that 3a-7b-4c, 3a-2b+c and a+b+2c are coplanar.

If a,b and c are non-coplanar vectors, prove that 3a-7b-4c, 3a-2b+c and a+b+2c are coplanar.

If a,b and c are non-coplanar vectors, prove that 3a-7b-4c, 3a-2b+c and a+b+2c are coplanar.

If a,b and c are non-coplanar vectors, prove that 3a-7b-4c, 3a-2b+c and a+b+2c are complanar.

If a, b and c are non-coplanar vectors and d=lambda vec a+mu vec b+nu vec c , then lambda is equal to