## Precalculus (10th Edition)

If the major axis of the parabola is parallel to the y-axis then it is in the form of $k(y-a)=(x-b)^2$, where $(b,a)$ is the vertex of the parabola and $k$ is a constant (positive if open up, negative if open down). If the major axis of the parabola is parallel to the x-axis then it is in the form of $k(x-a)=(y-b)^2$, where $(a,b)$ is the vertex of the parabola and $k$ is a constant. (positive if open right, negative if open left) Here the major axis is parallel to the y-axis, $k=\pm4$ in all cases, but here it is open left, hence $k=-4$ and the vertex is in $(1,1)$. Hence the equation: $-4(x-1)=(y-1)^2$ Thus the answer is g).