Mathematics
15 Online
OpenStudy (anonymous):
any idea on how to solve this?
Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy (anonymous):
\[(\frac{ i^3 }{ 3 })^3\]
hartnn (hartnn):
\(\huge (\frac{a}{b})^x=\frac{a^x}{b^x} \\ (a^b)^c=a^{bc}\)
hartnn (hartnn):
\(\huge (\frac{ i^3 }{ 3 })^3=\frac{(i^3)^3}{3^3}=?\)
OpenStudy (anonymous):
that would be i^9/27 ?\[\frac{ i^9 }{ 27 }\]
hartnn (hartnn):
yup, thats correct :)
now is 'i' just a variable here or square root of -1 ??
Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy (anonymous):
its a square root of -1
hartnn (hartnn):
so u know what is i^2 ?
OpenStudy (anonymous):
its -1
hartnn (hartnn):
and i^3 = ?
hartnn (hartnn):
and i^4 = ?
Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy (anonymous):
1^3 = -i
i^4 = 1
hartnn (hartnn):
now we write i^9 as i*(i^4)^2
got this ?
OpenStudy (anonymous):
so it would be a -i ?
hartnn (hartnn):
why - *minus* ?
OpenStudy (anonymous):
as in -i/27
Join the QuestionCove community and study together with friends!
Sign Up
hartnn (hartnn):
i^4 =+1
its square = +1
1*i=i
hartnn (hartnn):
so it would be i/27
OpenStudy (anonymous):
ohhh well its because i thought that i to the power of an odd number ( i.e., i^9 ) would equal a negative i
hartnn (hartnn):
now u got it ?
hartnn (hartnn):
i mean any more doubts ?
Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy (anonymous):
yeah, so is there no such thing as a -i ?
hartnn (hartnn):
yes it it,
i^-1 = -i
i^3 = -i
i^7 = -i
i^11= -i
i^15 =-i
....
did u get the pattern ?
OpenStudy (anonymous):
umm i think. not too sure.
hartnn (hartnn):
after every 4th power, the value gets repeated,
like i^0 = i^4 = i^8 = i^12 =.... = 1
i^1 = i^ 5 = i^9 =.....=i
and so on.
ok ?
OpenStudy (anonymous):
okay yeah thats what i thought, i just didnt want to sound dumb lol thanks!
Join the QuestionCove community and study together with friends!
Sign Up
hartnn (hartnn):
welcome :)