Digital SAT Math Test 2 Question 9

The given equation defines the function $g$. For what value of $x$ does $g(x)$ reach its maximum?
$$g(x)=-x^2+4x+11$$
Answer:
Answer:
2

Explanation

The correct answer is $2$.

Given that the lead coefficient is negative, the quadratic function is a parabola that is concave down, having its vertex as its maximum point.

✨ Expert's Tip ✨

The minimum or maximum of quadratic functions is determined by the lead coefficient of the function. When the lead coefficient $a$ is positive, the graph would be concave up, thus having a minimum at the vertex of the graph.

When the lead coefficient $a$ is negative, the graph would be concave down, thus having a maximum at the vertex of the graph.

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