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8 Answers
- Ivan DLv 51 decade agoFavorite Answer
x = a+bi
x^2 = a^2 + 2abi - b^2 = i
2ab= 1
a^2 - b^2 = 0
a = b or a =-b
in First case a = b = 1/sqrt(2)
in second case a = 1/sqrt(2) and b = -1/sqrt(2)
Square roots of i are
x = (1+i)/sqrt(2) and
x = (1-i)/sqrt(2)
- CurlyLv 61 decade ago
-1 = i * i
so
i = sqrt(-1)
therefore
-1 = j * j * j *j
or
j = sqrt(sqrt(-1))
the value "i" is very very useful, and pops up everywhere in sciences. Its on the same scale of value as pi, and a little less useful than e.
Fields that its useful in:
heat transfer
elasticisty
fluid flow
acoustics
structural dynamics
optics
ac electronic circuits
SISO/LTI control systems
MIMO/not-LTI control systems
Although you could find nth roots of negative 1 you might not find another so useful.
To find another so useful its probably wise to first understand how i is used in each of the above fields and what properties make it so useful.
- John HLv 41 decade ago
You do not, as it might seem, need a new set of imaginary units to obtain the squareroot of an imaginary number.
For i, it is +/- 1/sqrt(2) (1 + i)^2
Expanding the square of the expression proves that it is the squareroot of i.
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- santmann2002Lv 71 decade ago
Take it in polar form
i= 1<pi/2 +2kpi so sqrt(i) = 1<pi/4 +kpi ( k=0 and 1) =1<pi/4 and
1<5pi/4
so in binomial form
sqrt(i) =+-sqrt(2) /2 ( 1+i)
- gudspelingLv 71 decade ago
sqrt(i) = (a+bi) ----- a and b are real numbers
(a+bi)² = i
a² + 2abi - b² = i
a² - b² = 0
a = b
or a = -b
a=b
2abi = i
2a² = 1
a = 1/sqrt(2)
b = 1/sqrt(2)
sqrt(i) = ±(1+i)/sqrt(2)
a = -b
2abi = i
-2a² = 1
a = sqrt(-1/2) ---- not real
i has 2 square roots:
±(1+i)/sqrt(2)
- Anonymous1 decade ago
i is an imaginary number that is defined as the square root of -1.
- The WolfLv 61 decade ago
de moivres thereom backwards
i = e^iÏ/2
so
âi = e^i(Ï/2 + 2Ïk)/2 = e^i(Ï/4 + Ïk) for k = 0,1
= e^iÏ/4 = cos(Ï/4) + isin(Ï/4) = 1/â2 + i1/â2
and
= e^i(Ï/4 + Ï)= e^i5Ï/4 = cos(5Ï/4) + isin(5Ï/4) =1/â2-i1/â2
so
âi = 1/â2 ± i1/â2
.