Number Theory T...

$$\sqrt{-3}\sqrt{-75}=$$

The sum of two complex numbers $$a + ib$$ and $$c +id$$ is a real number if

The locus of complex number z such that z is purely real and real part is equal to - 2 is

$$\dfrac{1}{i-1}+\dfrac{1}{i+1}$$ is

The sum of two complex numbers $$a + ib$$ and $$c+ id$$ is purely imaginary if

If $$(x+iy)(2-3i)=4+i$$ then (x, y) =

Which of the following is not a prime number ?

Which of the following is not a composite number?

The number of prime numbers between 0 and 20 is

The units digit of every prime number (other than $$2$$ and $$5$$) must be necessarily