Question

Multiply (4 + i)(1 – 5i).

i got the answer I just want to see if I am correct.

Answer 1

@Michele_Laino

Answer 2

please post your answer with the `WORK` :=)) i'll check it

Answer 3

(4+i)*(1-5i)

4-20i+1i-5i^2

4-19i-5i^2

4-19i-5i^2 is my Answer

Answer 4

im sure your right i think

Answer 5

alright very nice!!!
\[i=\sqrt{-1}\] so i^2 = -1
so replace i^2 with -1 :=))

Answer 6

ok thanks, My answers are
9-19i

-1-19i

4-5i^2

4-19i-5i^2

so the last one is correct right

Answer 7

hmm no
use the fact `i = sqrt{-1}`
so i^2 = -1
substitute i^2 for -1 :=))

Answer 8

\[i=\sqrt{-1} ~~~~~ i^2=(\sqrt{-1})^2 \rightarrow i^2=-1\]
i is an imaginary number that is equal to sqrt{-1} when you take square of it you willget
i^2 = -1

Answer 9

ok can you walk me through the steps then? because now Im a bit confused xD

Answer 10

the last steps after what I did? Im not very good with this :/

Answer 11

okay your steps are correct
i'll take it from 4-19i-5i^2

\[\huge\rm 4-19i -5\color{ReD}{i^2}\]
i'm going to replace i^2 with -1
using the fact \[\large\rm i =\sqrt{-1} ~~and~~ i^2=-1\]
\[\huge\rm 4-19i -5\color{ReD}{(-1)}\]
now simplify

Answer 12

4-19i-5(-1)

-1-19i(-1)

-2-19i <- that is it?

Answer 13

mm no first multiply -5 times -1 and then combine like terms