Find all complex numbers z such that z2 1 2 sqrt6 i Soluti
Find all complex numbers z such that z2 = -1 + 2 sqrt(6) i.
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Solution
Let z = a + bi
Substitute into given equation: (a + bi)2 = -1 + 2 sqrt(6) i
Expand: a2 - b2 + 2 ab i = - 1 + 2 sqrt(6) i
Real part and imaginary parts must be equal.
a2 - b2 = - 1 and 2 ab = 2 sqrt(6)
Equation 2 ab = 2 sqrt(6) gives: b = sqrt(6) / a
Substitute: a2 - ( sqrt(6) / a )2) = - 1
a4 - 6 = - a2
Solve above equation and select only real roots: a = sqrt(2) and a = - sqrt(2)
Substitute to find b and write the two complex numbers that satisfies the given equation.
z1 = sqrt(2) + sqrt(3) i ,
z2 = - sqrt(2) - sqrt(3) i
