Question

Вычислите:
а) (5+i)(-2+3i)
б) 4i/1+i

Answer 1

$a)~ (5+i)(-2+3i)=-10+15i-2i-3=13i-13\ b)~dfrac{4i}{1+i}=dfrac{4i(1-i)}{(1+i)(1-i)}=dfrac{4i+4}{1+1}=2i+2$