SOLUTION: i^91=? This question was asked previously (question 3340), and the given soluttion was to find where i^91 came in the cycle of i. However I learned another way to do it, and I was

Question 4632: i^91=?
This question was asked previously (question 3340), and the given soluttion was to find where i^91 came in the cycle of i. However I learned another way to do it, and I was wondering if it is correct.
Take the given question i^91:
i^91 = i^90 + 1
= i^90 * i^1
= (i^2)^45*i^1
= -1^45 * i^1
= -1 * i
= -i

Found 2 solutions by longjonsilver, khwang:
Answer by longjonsilver(2297) (Show Source): You can put this solution on YOUR website!
this line: i^91 = i^90 + 1 is not needed (and is in fact incorrect). Take it out then the rest is a perfect answer, yes. Well done.

Jon.

Answer by khwang(438) (Show Source): You can put this solution on YOUR website!
Since 91 = 3 mod 4
i^91 = i^3 = -i

That's the whole story for this kind of baby math.
Forget any solution more than two lines.
If you still confused, think more and work hard
Kenny
RELATED QUESTIONS
Question: After closing down his lemonade stand, David finds that he has 3 and 1/2 times... (answered by stanbon,josmiceli,Alan3354)
I have previously asked this question, question #853406, but didn't really get help.... (answered by josgarithmetic,MathTherapy)
I previously asked this question but it came out wrong and when it was answered I saw how (answered by haileytucki)
I am having a serious brain freeze. The results to a question that I had was X=91/26... (answered by Alan3354)
Question: One Number is 7 more than another. The difference between their squares is 91.... (answered by Cromlix)
How would this problem be written as an equation: Smith and Jones combined age is 91.... (answered by J2R2R)
Subtract the polynomials. 8x^3+x^2+1 from 3x^3-x-6 I've tried it twelve times on... (answered by josgarithmetic)
The question I was asked was -2+-1+3/4 and my answer was -9/4. Is this... (answered by chessace,rfer)
I was kind confuse about " X; mean 91" can you please help? Thanks 4. Write and solve... (answered by jim_thompson5910)