AP EAMCET201822 Apr 2018Evening ShiftMathematicsComplex NumberActual
If a point P denotes a complex number z=x+i y in the argand plane and if z+1 z+i is a purely real number, then the locus of P is
Options
- Ax+y+1=0
- Bx^2+y^2+x+y=0
- Cx^2+y^2+2 y+1=0,(x, y) (0,-1)
- Dx+y+1=0,(x, y) (0,-1)
Correct answer
D. x+y+1=0,(x, y) (0,-1)
Step-by-step solution
Since aligned & z+1 z+i = x+i y+1 x+i y+i = (x+1) x+i(y+1) & x-i(y+1) x-i(y+1) aligned If z+1 z+i is a purely real number, z -i aligned & Then, I_m ( z+1 z+i )=0, z=-i & x y-(x+1)(y+1)=0, (x, y) (0,-1) & x y-x y-x-y-1=0 & x+y+1=0, (x, y) (0,-1) aligned