Question

Question on the practice math GRE, see picture attached

Answer 1

Since the vertex of a parabola is found in standard form most easily by the coordinates (-b/(2a),f(-b/(2a)), we can find b by plugging in 2 as the x coordinate from the graph. This gives
2=-b/(2a)
Solving for b gives b=-12.
Then we can evaluate f at 5, giving 27.