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.

AlgebraQuadratic FunctionsOptimizationGraph Analysis
2025/4/7

1. Problem Description

The problem is to analyze the quadratic function y=ax2+bx+cy = ax^2 + bx + c given its graph and certain conditions, and to determine the values of aa, bb, and cc 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 y=ax2+bx+cy = ax^2 + bx + c:
- The parabola opens downward, which means a<0a < 0. Thus, A is (9) - "<".
- The graph intersects the x-axis at two points. This is not directly relevant until later.
- When x=1x = 1, from the graph y=a+b+c=0y = a + b + c = 0. Thus, D is (8) - "=".
- When x=1x = -1, from the graph y=ab+c=0y = a - b + c = 0. Thus, E is (8) - "=".
- The vertex appears to be between x=1x=-1 and x=0x=0, this is not something that can be extracted in the prompt
From a+b+c=0a + b + c = 0 and ab+c=0a - b + c = 0, we can deduce that:
a+b+c=ab+ca + b + c = a - b + c
2b=02b = 0
b=0b = 0. Thus, B is (8) - "=".
Since a+c=0a+c=0 and a0a \ne 0, then c=ac = -a and since a<0a < 0, c>0c > 0. Thus, C is (7) - ">".
4a+2b+c=4a+0+c=4a+c=4aa=3a4a + 2b + c = 4a + 0 + c = 4a + c = 4a - a = 3a. Since a<0a<0, 3a<03a < 0, so 4a+2b+c<04a+2b+c < 0, F is (9) - "<". This is not needed.
The discriminant b24ac=024a(a)=4a2>0b^2 - 4ac = 0^2 - 4a(-a) = 4a^2 > 0 since a0a \ne 0. Thus G is (7) - ">". This is also not needed.
(2) Minimizing a28b8ca^2 - 8b - 8c with a<0a < 0, b=0b = 0, and c=ac = -a.
Substituting b=0b = 0 and c=ac = -a into the expression, we have:
a28(0)8(a)=a2+8aa^2 - 8(0) - 8(-a) = a^2 + 8a.
To minimize f(a)=a2+8af(a) = a^2 + 8a, we can find the vertex of the parabola.
The vertex is at a=82(1)=4a = -\frac{8}{2(1)} = -4. Since a<0a<0, a=4a=-4 is valid.
Thus, H is (6) - "-4".
When a=4a = -4 and b=0b = 0, then y=4x2+0x+cy = -4x^2 + 0x + c. Also c=ac = -a, so c=4c = 4.
So y=4x2+4y = -4x^2 + 4.
We are told that y=ax2+bx+cy=ax^2+bx+c can be written as y=ax2+bxb+Iy = ax^2+bx-b+I, and a=4,b=0,c=4a=-4, b=0, c=4, so y=4x2+0x+4y = -4x^2 + 0x + 4, then c=b+Ic=-b+I means 4=0+I4=-0+I, hence I=4I=4.
Thus I is (4) - "4".
We have a=4a = -4 and b=0b = 0.
Since we need to maintain the condition a+b+c=0a+b+c = 0 we have that bb can be any value and we need c=abc=-a-b which keeps a+b+c=a+bab=0a+b+c = a+b-a-b=0.
The problem statement says we need (i) a<0 and (ii) a+b+c=0a+b+c=0. Then c=abc = -a-b and we want to minimize a28b8c=a28b8(ab)=a28b+8a+8b=a2+8aa^2-8b-8c=a^2-8b-8(-a-b) = a^2-8b+8a+8b = a^2+8a. So a needs to be the minimum, a=4a=-4. The range of bb that satisfies these equations is not restricted, it appears, by previous results, but we know that ab+c=abab=2ba-b+c=a-b-a-b = -2b which means that 2b=0-2b=0 for ab+c=0a-b+c=0, b=0b=0, thus 2b<0-2b<0 so b is unrestricted. Now we are told that y=ax2+bx+cy = ax^2+bx+c where a<0a<0, b=0,c>0b=0, c>0, a=4,b=0,c=4a=-4, b=0, c=4 from above. Then y can be expressed as y=4x2+bxb+4y = -4x^2+bx-b+4 when y=ax2+bx+c=4x2+0x+4y = ax^2 + bx + c = -4x^2+0x+4, b+4=4-b+4=4 and b=0b=0. Since the parabola intersects x-axis at -1 and 1, it should be such that a<0a<0, and parabola y=ax2+bx+cy = ax^2+bx+c satisfies y<0y<0, b0b \ge 0 and bb can not be greater than 1,
0=4+b0= -4+b, b=4b = 4, so
We need bb such that a<0,a<0, b=a/2a/2,
Since a<0a<0, 0<b<10<b<1.
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,
a<0,b=0,c=a>0 a<0 , b=0, c = -a>0 . If b=0b=0, than
0<b<10<b<1, 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)

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