3=(7x-5y)^2 - y ...............(Given equation)
Put x=rcostheta and y=rsintheta ; we get :-
rArr3=(7rcostheta-5rsintheta)^2-rsintheta
rArr3=49r^2cos^2theta+25r^2sin^2theta-70r^2costheta.sintheta-rsintheta
rArr3=24r^2cos^2theta+(25r^2cos^2theta+25r^2sin^2theta)-70r^2costheta.sintheta-rsintheta
rArr3=24r^2cos^2theta+25r^2-70r^2costheta.sintheta-rsintheta
:.25r^2+24r^2cos^2theta-70r^2costheta.sintheta-rsintheta-3=0
is the Polar form