Let $A = \left(1,3,0,2\right)$ and $B = \left(-3,4,-3,-1\right)$ be points in $\mathbb{R}^4$.

1. Find the vector $\overrightarrow{AB}$ in $\mathbb{R}^4$.
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2. Find a vector in the direction of $\overrightarrow{AB}$ that is $2$ times as long as $\overrightarrow{AB}$.
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3. Find a vector in the direction opposite $\overrightarrow{AB}$ that is $2$ times as long as $\overrightarrow{AB}$.
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4. Find a unit vector in the direction of $\overrightarrow{AB}$.
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5. Find a vector in the direction of $\overrightarrow{AB}$ that has length $2$.
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