A Projectile is given an initial velocity of $(\hat{i}+2 \hat{j})m/s,$ where $\hat i$ is along the ground and $\hat j$ is along the vertical. If $g = 10 m/s^2,$ the equation of its trajectory is :

Question

$\begin{array}{1 1} (1)\;y=x-5x^2 \\ (2)\;y=2x-5x^2 \\ (3)\;4y=2x-5x^2 \\ (4)\;4y=2x-25x^2 \end {array}$