Let $X_1$ and $X_2$ are the optimum solutions of LPP, then
(a) $X = λX_1+(1- λ)X_2$, $λ \in \Bbb R$ is also an optimal solution
(b) $X = λX_1+(1-λ)X_2$, $0 \leq λ \leq 1$ gives an optimal solution
(c) $X = λX_1+(1+λ)X_2$, $0 \leq λ \leq 1$ gives an optimal solution
(d) $X = λX_1+(1+λ)X_2$, $λ \in \Bbb R$ gives an optimal solution
Please explain (in detail) how to solve it...
Thanks in advance.