Question 895993
Variable point P(x,y).
The line x=-12 is the variable point (-12,y).


{{{sqrt((x-(-3))^2+(y-0)^2)=(1/2)sqrt((x-(-12))^2+(y-y)^2)}}}

{{{sqrt((x+3)^2+y^2)=(1/2)sqrt((x+12)^2+0)}}}


{{{((x+3)^2+y^2)=(1/4)((x+12)^2)}}}


{{{4(x+3)^2+4y^2=(x+12)^2}}}

{{{4(x^2+6x+9)+y^2=x^2+24x+144}}}

{{{4x^2+24x+36+y^2=x^2+24x+144}}}

{{{3x^3+36+y^2=144}}}

{{{3x^2+y^2=108}}}

{{{highlight(x^2/36+y^2/108=1)}}}