What is (2 i - 3 k) × j?

Question 95

EasyOriginal question

What is $(2\hat{i} - 3\hat{k}) \times \hat{j}$ ?

3\hat{i} + 2\hat{k}

Correct answerYour answer

-3\hat{i} - 2\hat{k}

Correct answerYour answer

-3\hat{i} + 2\hat{k}

Correct answerYour answer

3\hat{i} - 2\hat{k}

Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer A

Correct answer: A

$(2\hat{i} - 3\hat{k}) \times \hat{j} = 2(\hat{i} \times \hat{j}) - 3(\hat{k} \times \hat{j})$ .
$\hat{i} \times \hat{j} = \hat{k}$ and $\hat{k} \times \hat{j} = -\hat{i}$ , so it is $2\hat{k} + 3\hat{i} = 3\hat{i} + 2\hat{k}$ .

Worth noting

$-3\hat{i} - 2\hat{k}$ is $\hat{j} \times (2\hat{i} - 3\hat{k})$ , the product in the other order.

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