Question

Plzzzz help meee.......​

Answer 1

Answer:
`-3\hat{i}-6\hat{j}+2\hat{k}`

Explanation:

Given

`\vec{a}=2\hat{i}+4\hat{j}-5\hat{k}\\\vec{b}=\hat{i}+\hat{j}+\hat{k}`

`\vec{c}=\hat{j}+2\hat{k}`

The addition of the three is
`\vec{a}+\vec{b}+\vec{c}`

`\vec{a}+\vec{b}+\vec{c}=(2\hat{i}+4\hat{j}-5\hat{k})+(\hat{i}+\hat{j}+\hat{k})+(\hat{j}+2\hat{k})`

`\vec{a}+\vec{b}+\vec{c}=3\hat{i}+6\hat{j}-2\hat{k}`

vector opposite to the vector
`\vec{a}+\vec{b}+\vec{c}\ \ \text{is}\ -(\vec{a}+\vec{b}+\vec{c})`

`\therefore -(\vec{a}+\vec{b}+\vec{c})=-3\hat{i}-6\hat{j}+2\hat{k}`