Question

Does (2+5i)+(-2-4i) equal to 0+1i, or i?

Answer 1

(2+5i)+(-2-4i)

2+5i-2-4i
2-2 + (5-4)i
0+i

You can omit the 0+ and write is as just i, but if you want to make it clear that you are in fact working with a complex number, the standard form a+bi is used.

Although, just the presence of "i" itself makes it evident that we are using complex numbers, of which i is purely imaginary.