Answer: the third option {x | x > 1}
Explanation:
The graph permits to identify easily the interval in which the function grows (increases).
Per definition, the function grows when the value of y increases as x increasses. In a graph it is the value of y goes up when the value of x goest to the right.
The graph shows a parabola opening upward, so it has a minimum value, which is the vertex of the parabola. To the left of the vertex, the graph decreases (y is less as x increases), to the right of the vertex, the graph increases (y increases as x increases).
You can read the coordinates of the vertex on the graph. They are x = 1, y = - 4.
Therefore, the graph increases for the x-values greater than 1.
That is x > 1.
And in set notation it is the third option {x | x > 1}, which is read "x such that x is greater than 1".
