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**Glitch** **The question:**

Show that T = {$\displaystyle \sum_{i=1}^4 \lambda _i v_i : \lambda _i \in \mathbb{R}, 1 \le i \le 4$}, where $\displaystyle v_1, v_2, v_3, v_4 $ are given fixed vectors in $\displaystyle \mathbb{R}^3$ is either a subspace or not a subspace of $\displaystyle \mathbb{R}^3$.

I'm not sure what they mean by "given fixed vectors" means, or how to use them in my reasoning. I'm also a little confused as to how I can check the Subspace Theorem when there's summation involved. Any assistance would be great.