Question

if i= (sqrt)-1, then which expression is equal to 9i(13i)

A. -117
B. 117i
C. 117
D. -117i

Answer 1

distribute parentheses by outside term

Answer 2

so do you equal them like: 9i(13i)=(sqrt)-1

Answer 3

\[\huge\rm i = \sqrt{-1} \]
just i equal sqrt{-1}
multiply 9i(13i) it's not going to = sqrt-1}

Answer 4

im confused...

Answer 5

okay first multiply 9i(13i) = ?

Answer 6

117i

Answer 7

or first you can replace i by sqrt -1

Answer 8

i times i = ??

Answer 9

i^2

Answer 10

9 i times 13 i
9 times 13 and i times i

Answer 11

yes right i^2 = -1

Answer 12

117i^2 is the answer??

Answer 13

\[\huge\rm 9\sqrt{-1}(13\sqrt{-1})\]
okay if we replace i by sqrt{-1}
right now multiply
what would u get when you multiply \[\huge\rm \sqrt{-1} \times \sqrt{-1}= ?\]

Answer 14

\[\huge\rm i^2 = i \times i \]
\[\large\color{red}{\rm i = \sqrt{-1}}\]
because i equal sqrt of -1
you can substitute sqrt -1 for i
when you multiply sqrt{-1} by sqrt{-1} both square would cancel each other out
so \[\sqrt{-1} \times \sqrt{-1} = -1\]
so that's why i^2 = -1

Answer 15

okay.

Answer 16

so replace i^2 bu -1

Answer 17

y*

Answer 18

so that answer is 117i

Answer 19

i^2 = ???

Answer 20

-1

Answer 21

yes so substitute -1

Answer 22

-117

Answer 23

yes

Answer 24

okay thanks alot!!!!

Answer 25

my pleasure :-)