Final answer:
To find the minimum value of a quadratic function, we need to determine the coordinates of its vertex. From the graph, we can use the x-coordinate of the vertex to find the minimum value of j.
Step-by-step explanation:
The minimum value of a quadratic function occurs at its vertex. To find the vertex, we need to determine the x-coordinate by using the formula x = -b/2a, where a and b are the coefficients of the quadratic function. From the graph, we can see that the x-coordinate of the vertex is an integer. Once we have the x-coordinate, we can substitute it into the quadratic function to find the corresponding value of j. This will give us the minimum value of j.