Question

Plzzzz help meee.......​

Answer 1

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

Step-by-step 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  $\vec{a}+\vec{b}+\vec{c}\ \ \text{is}\ -(\vec{a}+\vec{b}+\vec{c})$

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