Question

(-12+48i)+(15+21i) in simplifying complex numbers

Answer 1

So if the "i" becomes confusing, just think of it as x
so it would become (-12+48x) +(15+21x)
then you would split up the terms by constants and coefficients
-12+15 +48x+21x
3+69x and then you substitute back for i
3+69i