Hey guys, Im sorry to bothered you but Im kinda desperate and really need your help.
Im preparing for math exam and Ive got a 3 various problem
I know the right answers but Im not able to find out the method. I would really appreciate your help.
1. if cos x = -2/5 than cos 2x = ?? (i know it is -17/25)
or sin x = 3/5 and cos2x= ?? (7/25) but I have no clue how to do it.
2. the number of X (X is from (pi, 2pi) which is valid for sin^2x-sinx=0
(it is 0)
or X is from (0, 2pi) for sin^3x+sinx=0
(it is 1)
3. the last one
the imaginary part of the number
(-1 -i)^8 is (0)
or (1+i)^8 is (16)
(-2 -2i)^8 is (2^12)
(1+i)^32 is (0)
Much appreciate your help and time!
ok, thanks for you help, anyway im dumb as hell so it wasn't actually really usefull for me...
update: OK, it was helpful I got the first two... the 3th one is pure mess.
I just found another I guess it is pretty simple but I can't solve it...
thank you in advanced
I had the test today... I got 85% Anyway could you solve this for me
(1+i)^33 I still don't have a clue. the options were I guess
a)2^16
b)2^7
c)-2^16
d)-2^17
e)none of them
thx
nvm. google solve it
(1 + i)^33 = 65 536 + 65 536 i
Hello, mika619!
Does #3 go like this?
3. Find the imaginary part of these numbers:
. .
All four of these turn out to be real numbers,
. . so their imaginary compoenents are all zero.
We find that: .
. . So we have: .
Raise both sides to the 4th power:
. .
. .
Therefore: .
We find that: .
. . So we have: .
Raise both sides to the 4th power:
. .
. .
Therefore: .
Get the idea?