Q49 / 160 · AP EAMCET 2019 (21 Apr Shift 2) · Mathematics

Let the point P represent z=x+iy, x, y∈R inthe Argand plane. Let the curves C1 and C2 be the loci of P satisfying the conditions (i) 2z+iz-2 is purely imaginary and (ii) Argz+iz+1=π2, respectively. Then the point of intersection of the curves C1 and C2, other than the origin, is

  • A
    (1,2)
  • B
    27,-57
  • C
    (-3,4)
  • Correct answer
    D
    537,-3037

Solution

It is given that
z=x+iy, x, y∈ℝ


And 2z+iz-2=2(x+iy)+i(x-2)+iy

Re2z+iz-2=2x+i(2y+1)(x-2)+iy×(x-2)-iy(x-2)-iy

0=2 x(x-2)+y(2 y+1)=0

0=x2+y2-2x+y2  ...i

And, z+iz-i=x+i(y+1)(x+1)+iy×(x+1)-iy(x+1)-iy


Now, argz+iz-i=tan-1(x+1)(y+1)-xyx(x+1)+y(y+1)=π2

x2+y2x+x+y=0   ...ii

Equation of common chord of circles (i) and (ii) is
S1-S2=0
-3x-y2=0

y+6x=0  ...iii

From Equations (i) and (iii), the intersection of the circles is, x2+36x2+x-6x=0

x=0, 537
So the values of y are 0, -3037
This implies the point of intersection of the curves C1 and C2 other than the origin is 537,-3037

 

 

Hence, the correct answer is option: 'D'.

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