If a→ satisfies a→×(i^+2j^+k^)=i^−k^, then a→ is equal to
λi^+(2λ−1)j^+λk^,λ∈R
λi^+(1−2λ)j^+λk^,λ∈R
λi^+(2λ+1)j^+λk^,λ∈R
λi^−(1+2λ)j^+λk^,λ∈R
a→×(i^+2j^+k^)=i^−k^=(j^×(i^+2j^+k^)) or (a→−j^)×(i^+2j^+k^)=0→ or a→−j^=λ(i^+2j^+k^) or a→=λi^+(2λ+1)j^+λk^,λ∈R