y=x-2y+xy^2y=x−2y+xy2
x=rcosthetax=rcosθ
y=rsinthetay=rsinθ
Thus,
rsintheta=rcostheta-2rcosthetaxxrsintheta+rcosthetaxx(rsintheta)^2rsinθ=rcosθ−2rcosθ×rsinθ+rcosθ×(rsinθ)2
rsintheta=rcostheta-2r^2sinthetacostheta+r^2sin^2thetacosthetarsinθ=rcosθ−2r2sinθcosθ+r2sin2θcosθ
rsintheta-rcostheta=r^2(-2sinthetacostheta+sin^2thetacostheta)rsinθ−rcosθ=r2(−2sinθcosθ+sin2θcosθ)
r(sintheta-costheta)=r^2sinthetacostheta(-2+costheta)r(sinθ−cosθ)=r2sinθcosθ(−2+cosθ)
r(sintheta-costheta)+r^2sinthetacostheta(2-costheta)r(sinθ−cosθ)+r2sinθcosθ(2−cosθ)
r(sintheta-costheta+rsinthetacostheta(2-costheta))=0r(sinθ−cosθ+rsinθcosθ(2−cosθ))=0
r=0r=0
sintheta-costheta+rsinthetacostheta(2-costheta)=0sinθ−cosθ+rsinθcosθ(2−cosθ)=0
rsinthetacostheta(2-costheta)=costheta-sinthetarsinθcosθ(2−cosθ)=cosθ−sinθ
r=(costheta-sintheta)/((2-costheta)sinthetacostheta)r=cosθ−sinθ(2−cosθ)sinθcosθ