Fundamental point: The initial velocity is not colinear with the force!
Solve for t in the first equation, t=x(t)/vx(0), and substitute in the
second equation to give:
y(t)=vy(0)x(t)/vx(0) -½g[x(t)/vx(0)]2= Ax+Bx2 Parabolic trajectory!
Examples: thrown ball, bowling ball with sidespin, billiards masse shot.