1.

Point P represent the complex number z=x+iy and point Qrepresents the complex number z+1/z. If P moves on the circle |z|=2, then the eccentricity of locus of point Q isA. `3//5`B. `4//5`C. `3//4`D. `1//2`

Answer» Let `Q-=alpha+ibeta`
Given that |z|=2, where z=x+iy
`:. x^(2)+y^(2)=4`
Now, `alpha+ibeta=z+(1)/(z)=(x+iy)+(1)/(x+iy)`
`=(x+iy)+((x-iy)/(4))=(5x)/(4)+(3iy)/(4)`
`:. alpha=(5x)/(4)and beta=(3y)/(4)`
Since `x^(2)+y^(2)=4`
`(16alpha^(2))/(25)+(16beta^(2))/(9)=4` ltbr So, locus of point Q is `(x^(2))/(25)+(y^(2))/(9)=(1)/(4)`
Eccentricity of theis conic is given by
`e^(2)=1-(9)/(25)=(16)/(25)`


Discussion

No Comment Found

Related InterviewSolutions