1
BITSAT 2025
MCQ (Single Correct Answer)
+3
-1

If ' $a$ ' is a complex number such that $|a|=1$. Find the value of $a$, so that the equation $a z^2+z+1=0$ has one purely imaginary root.

A

$\cos \left\{\cos ^{-1}\left(\frac{-\sqrt{5}+1}{4}\right)\right\}$

B

$\cos \left\{\sin ^{-1}\left(\frac{\sqrt{5}+1}{4}\right)\right\}+i \sin \left\{\cos ^{-1}\left(\frac{\sqrt{5}+1}{4}\right)\right\}$

C

$\sin \left\{\cos ^{-1}\left(\frac{\sqrt{5}-1}{4}\right)\right\}+i \sin ^{-1}\left(\frac{-\sqrt{5}+1}{2}\right)$

D

None of the above

2
BITSAT 2025
MCQ (Single Correct Answer)
+3
-1

Let $z$ be a complex number for which $\left|2 z \cos \theta+z^2\right|>1$, if $|z|

A

equal to $\sqrt{2}-1$

B

greater than $\sqrt{2}+1$

C

less than $\sqrt{2}-1$

D

greater than $\sqrt{2}-1$

3
BITSAT 2024
MCQ (Single Correct Answer)
+3
-1
The points represented by the complex number $ 1+i,-2+3 i, \frac{5}{3} i $ on the argand plane are
A
Vertices of an equilateral triangle
B
Vertical of an isosceles triangle
C
Collinear
D
None of the above
4
BITSAT 2024
MCQ (Single Correct Answer)
+3
-1
The modulus of the complex number $ z $ such that $ |z+3-i|=1 $ and $ \arg (z)=\pi $ is equal to
A
3
B
2
C
9
D
4

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