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sa se determine nr complexe z
1.z+3i=5z conjugat
2.z+2|z|=13+4i


Răspuns :

La 1)
z + 3i = 5z ( z conjugat)
 Notam z = a + bi =>
 a+bi+3i = 5(a-bi) => a + (3+b)i = 5a - 5bi

Egalam partile reale cu partile imaginare:

=>[tex] \left \{ {{a=5a} \atop {3+b=-5b}} \right. [/tex] [tex]=\ \textgreater \ \left \{ {{a=0} \atop {6b=-3}} \right. =\ \textgreater \ \left \{ {{a=0} \atop {b=- \frac{1}{2}}} \right.=\ \textgreater \ z = 0 - \frac{1}{2}i =\ \textgreater \ z = -\frac{1}{2}i [/tex]
 
La 2)
|z| = [tex] \sqrt{ a^{2}+ b^{2} } [/tex]

Notezi la fel z= a + bi;