Question

Find the product of the complex number and its conjugate.
1 + 2i

Answer 1

1 - 4i

-3

5

1 + 4i

Answer 2

hint:

(a+bi)*(a-bi) = a^2 + b^2

Answer 3

Last one ? @jim_thompson5910

Answer 4

what are a and b in this case

Answer 5

a+bi
1+2i

a = ?
b = ?

Answer 6

1-2i ?

Answer 7

a = 1
b = 2i

Answer 8

close

Answer 9

a = 1
b = 2

Answer 10

(a+bi)*(a-bi) = a^2 + b^2

(1+2i)*(1-2i) = 1^2 + 2^2 ... plug in a = 1 and b = 2

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

Answer 11

1 - 2i +2i - 4i^2

Answer 12

the -2i and 2i terms add to 0i or just 0

Answer 13

so 1-4i^2

Answer 14

you now have 1 - 4i^2

Answer 15

good

Answer 16

i^2 = -1

1 - 4i^2

turns into

1 - 4(-1)

Answer 17

5

Answer 18

correct