Question

find a and b. if (1+2i) (-2+i)

Answer 1

Answer:

a=-4,b=5

Step-by-step explanation:

=(1+2i)(-2+i)

=1(-2+i)+2i(2+i)

=-2+i+4i+2i²

=-2+5i+2(-1).......[i²=-1]

=-2+5i-2

=-4+5i.

...{a=-4,b=5.. ; (a+bi)}

Answer 2

Answer:

Step-by-step explanation:

a=-4 b=-3

(1+2i)(-2+i)

1(-2+i)+2i(-2+i)

-2+i+(-4i)+2i^2. (i^2=√-1)

-2+(-3i)+(-2)

-4-3i

A=-4 b=-3