Yes, it's true.
How I open the expression with power of 4?Yes, it's true.
Hint: Express [imath]\sqrt{-7}[/imath] in terms of [imath]i[/imath].
\(\displaystyle ((1+\sqrt{-7})^2)^2\)How I open the expression with power of 4?
Thanks.\(\displaystyle ((1+\sqrt{-7})^2)^2\)
Similar for the other term.
I would use D'Moivere's theorem → a + ib = r * eiΘ