Find the position vector of a point R which-divides the line joining two points P and Q whose position vectors are `hati+2hatj-hatk` and `-hati+hatj+hatk` respectively, in the ratio 2:1 Internally

Explanation

To find the position vector of point R which divides the line joining two points P and Q in the ratio 2:1 internally, we will use the section formula. Let's denote the position vectors of points P and Q as follows:

- Position vector of P, \( \vec{P} = \hat{i} + 2\hat{j} - \hat{k} \)
- Position vector of Q, \( \vec{Q} = -\hat{i} + \hat{j} + \hat{k} \)

### Step 1: Identify the ratio and the position vectors
We are given that point R divides the line segment joining P and Q in the ratio 2:1. This means:
- \( m = 2 \) (the part towards Q)
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