Respuesta :

10 +20i you just multiply and look what to write simply

Answer:

Standard form of (1 +7i)(3 − i) is:

10+20i

Step-by-step explanation:

We have to multiply (1+7i) and (3-i)

(1+7i)(3-i)=1(3-i)+7i(3-i)

             = 3-i+21i-7i²

            =3+20i+7  (since, i²= -1)

           =10+20i

Hence, standard form of (1 +7i)(3 − i) is:

10+20i