Question

which expression below is equivalent to 4i(12-7i)
a)-28+48i
b)28+48i
c)48+28i
d)-48=28i

Answer 1

When you distribute 4i(12-7i), what do you get?

Answer 2

48i-28i^2?

Answer 3

what is i^2 equal to

Answer 4

i+i? lol idk

Answer 5

i by defintion is equal to sqrt(-1)

in other words,

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

Answer 6

oh wait its 1

Answer 7

so square both sides to get

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

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

\[\Large i^2 = -1\]

Answer 8

so the answer is c?

Answer 9

Since \[\Large i^2 = -1\] we go from 48i-28i^2 to 48i-28(-1)

Answer 10

now simplify 48i-28(-1)

Answer 11

oh okay so its b?

Answer 12

good

Answer 13

thanks a bunch!!!

Answer 14

you're welcome