AITS complex nos

plz solve

A(z1) , B(z2) and C(z3) are 3 points lying on the curve
|z|=√3

1. If z2z1+ z2z + z3=0 has one root of modulus unity.
z1,z2,z3are in:
a)AP
b)Gp
c)HP
D)all of the above

2.If z2z1+ z2z + z3=0 and
z2z2+ z3z + z1=0 each have a common root unity then
triangle ABC is:
a)isosceles
b)equilateral
c)right
d)scalene

ans
1.b
2.b

6 Answers

341
Hari Shankar ·

z^2z_1+zz_2+z_3 = 0 \Rightarrow \overline{z^2z_1+zz_2+z_3}= \overline{z^2}\overline{z_1} + \overline{z}\overline{z_2} + \overline{z_3}=0

Now |z| =1 \Rightarrow \overline{z} = \frac{1}{z} and |z_1| = \sqrt 3 \Rightarrow \overline{z_1} = \frac{3}{z_1} etc.

So we have after dividing by 3 throughout, \frac{1}{z^2z_1} + \frac{1}{zz_2}+\frac{1}{ z_3}=0

So if p=z^2z_1; q=zz_2; r=z_3 we have

p+q+r=0; \frac{1}{p} + \frac{1}{q} + \frac{1}{r} = 0 \Rightarrow pq+qr+rp=0

pq+qr+rp=0 \Rightarrow q(p+r) + rp = 0 \Rightarrow q^2=pr.

This means (zz_2)^2 = z^2z_1z_3 or z_2^2=z_1z_3

Hence z_1, z_2, z_3 are in GP

1
nikunj ·

Find the mistake
z2z1+ z2z + z3=0 is quadratic equation in z.Let its roots be 1,μ
μ+1=-(z2z1) and μ=z3/z1
Substituting value of μ ,z3z1+1=-z2z1 giving z1+z2+z3=0

1
cipher1729 ·

@prophet sir plz help, I can't understand

"p+q+r=0 therefore

1/p + 1/q + 1/r =0 .............."

how??

1
Che ·

@cipher jus see wat are p ,q and r

1
cipher1729 ·

oops[4][4]

1
cipher1729 ·

thanks to everyone who answered. I got it now

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