Question

-9i(13+2i) = ?

Answer 1

-117i -18i^2 = -117i + 18

Answer 2

hi

Answer 3

from the -117i-18^2 how u get it to = -117i + 18 ?

Answer 4

What does i equal?

Answer 5

hmm ?

Answer 6

Well your problem says -9i(13+2i). My question to you is what is i ?

Answer 7

if you are not working in complex numbers where i^2 = -1

then -9i(13 + 2i) = -117i - 18i

Answer 8

but isn't -9i x 2i = -18i^2 ?

Answer 9

yes it is. What is i ?

Answer 10

imaginary number ?

Answer 11

Which imaginary number?

Answer 12

-18 ?

Answer 13

i dont get what your asking =.=

Answer 14

That's why you are having trouble with this problem.

Answer 15

\[i=\sqrt{-1}\]

Answer 16

Therefore:
\[i^2=(\sqrt{-1})^2=-1\]

Answer 17

ohhh i see

Answer 18

-18(-1) = 18

Answer 19

And
\[18i^2=18(-1)=-18\]

Answer 20

And
\[-18i^2=-18(-1)=18\]

Answer 21

i got it, thanks @Mertsj :D

Answer 22

yw