The primitive solutions to x3+y9=z2

We determine the rational integers x,y,z such that x3+y9=z2 and gcd(x,y,z)=1. First we determine a finite set of curves of genus 10 such that any primitive solution to x3+y9=z2 corresponds to a rational point on one of those curves. We observe that each of these genus 10 curves covers an elliptic curve over some extension of Q. We use this cover to apply a Chabauty-like method to an embedding of the curve in the Weil restriction of the elliptic curve. This enables us to find all rational points and therefore deduce the primitive solutions to the original equation.