Solution 7.1a
From Mechanics
\displaystyle t=0\ \ gives
\displaystyle \mathbf{r}=6\times 0\mathbf{i}+\left( 15\times 0-4.9\times {{0}^{2}} \right)\mathbf{j}=0\mathbf{i}+0\mathbf{j}\ \text{m}
\displaystyle t=1\ \ gives
\displaystyle \mathbf{r}=6\times 1\mathbf{i}+\left( 15\times 1-4.9\times {{1}^{2}} \right)\mathbf{j}=6\mathbf{i}+10.1\mathbf{j}\ \text{m}
\displaystyle t=2\ \ gives
\displaystyle \mathbf{r}=6\times 2\mathbf{i}+\left( 15\times 2-4.9\times {{2}^{2}} \right)\mathbf{j}=12\mathbf{i}+10.4\mathbf{j}\ \text{m}