Question

Which of the following is wrong?

(a) $|\mathbf{a}|^2=a^2$, ' $a$ ' is a real number

(b) $|\mathbf{a}|^2=-a^2$

(c) $|\mathbf{a}|^2=a^2$, ' $a$ ' is a complex number

(d) None of the above

Answer 1

$|\mathbf{a}|^2=\mathbf{a} \cdot \mathbf{a}=a^2$ but $|z|^2 \neq z^2$

(As one side is real but other side is imaginary)

So, The correct option of this question will be (C).