The problem is to analyze the quadratic function $y = ax^2 + bx + c$ given its graph and certain conditions, and to determine the values of $a$, $b$, and $c$ that satisfy the given constraints. Specifically, we are asked to fill in the blanks A through K with the appropriate choices from the given options.
2025/4/7
1. Problem Description
The problem is to analyze the quadratic function given its graph and certain conditions, and to determine the values of , , and that satisfy the given constraints. Specifically, we are asked to fill in the blanks A through K with the appropriate choices from the given options.
2. Solution Steps
(1) Analyzing the graph of :
- The parabola opens downward, which means . Thus, A is (9) - "<".
- The graph intersects the x-axis at two points. This is not directly relevant until later.
- When , from the graph . Thus, D is (8) - "=".
- When , from the graph . Thus, E is (8) - "=".
- The vertex appears to be between and , this is not something that can be extracted in the prompt
From and , we can deduce that:
. Thus, B is (8) - "=".
Since and , then and since , . Thus, C is (7) - ">".
. Since , , so , F is (9) - "<". This is not needed.
The discriminant since . Thus G is (7) - ">". This is also not needed.
(2) Minimizing with , , and .
Substituting and into the expression, we have:
.
To minimize , we can find the vertex of the parabola.
The vertex is at . Since , is valid.
Thus, H is (6) - "-4".
When and , then . Also , so .
So .
We are told that can be written as , and , so , then means , hence .
Thus I is (4) - "4".
We have and .
Since we need to maintain the condition we have that can be any value and we need which keeps .
The problem statement says we need (i) a<0 and (ii) . Then and we want to minimize . So a needs to be the minimum, . The range of that satisfies these equations is not restricted, it appears, by previous results, but we know that which means that for , , thus so b is unrestricted. Now we are told that where , , from above. Then y can be expressed as when , and . Since the parabola intersects x-axis at -1 and 1, it should be such that , and parabola satisfies , and can not be greater than 1,
, , so
We need such that b=,
Since , .
Let's look for other constraints from a-b+c=0 and a+b+c=
0. a-b+c=0 and a+b+c=0 imply $a+c=b$ and $a+c=-b$, $b = -b$ means $b=0$.
b must be 0, but we also have to consider c must be greater than zero,
. If , than
, so from these considerations we have, J is 0 and K is
1. Thus J is (0) and K is (1).
3. Final Answer
A: (9)
B: (8)
C: (7)
D: (8)
E: (8)
F: (9)
G: (7)
H: (6)
I: (4)
J: (0)
K: (1)