Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Determinants

Question:

If a = cos\(\frac{4π}{3}\) + isin\(\frac{4π}{3}\), then \(\begin{vmatrix}1 & 1 & 1 \\ 1 & a & a^2 \\ 1 & a^2 & a \end{vmatrix}\) is equal to which of the following?

Options:

Purely real

Purely imaginary

0

None of these

Correct Answer:

Purely imaginary

Explanation:

a = cos\(\frac{4π}{3}\) + isin\(\frac{4π}{3}\) = ω

∴ \(\begin{vmatrix}1 & 1 & 1 \\ 1 & ω^2 & ω \\ 1 & ω & ω^2 \end{vmatrix}\) = 3(ω - ω2) purely imaginary