Calculate the product of $(2 - 3i)$ and $(2 + 3i)$ and express your answer in standard form.

Perform the indicated operations on the following complex numbers and have the answer in standard form.

$\frac{1-2i}{3-4i}$

Simplify the following expression and express the answer in standard form.

$\sqrt{4^2-4\cdot1\cdot10}$