Sign analysis of quadratic coefficients and expressions from a graph
The question presents the graph of a quadratic function and asks the student to determine the signs (positive, negative, or zero) of various expressions involving the coefficients, such as a, b, c, the discriminant, or evaluated sums like a+b+c.
Q1 For A $\sim$ K in the following sentences, choose the correct answer from among choices (0) $\sim$ (9) below. (1) Consider the quadratic function $$y = a x ^ { 2 } + b x + c$$ whose graph is as shown in the figure at the right. Then $a , b$ and $c$ satisfy the following expressions: (i) $a \mathbf { A } 0 , b \mathbf { B } 0 , c \mathbf { C } 0$; (ii) $a + b + c \mathbf { D } 0$; (iii) $a - b + c \mathbf { E } 0$; (iv) $4 a + 2 b + c \mathbf { F } 0$; (v) $b ^ { 2 } - 4 a c \mathbf { G } 0$. (2) Given the condition that $a , b$ and $c$ satisfy (i) and (ii) in (1), consider the case where the value of $a ^ { 2 } - 8 b - 8 c$ is minimized. We see that $a = \mathbf { H }$. When we express $y = a x ^ { 2 } + b x + c$ in terms of $b$, we have $$y = \mathbf { H } x ^ { 2 } + b x - b + \mathbf { I } \text {. }$$ Also, we see that the range of the values of $b$ is $\mathbf { J } < b < \mathbf { K }$. (0) 0 (1) 1 (2) 2 (3) 3 (4) 4 (5) - 2 (6) - 4 (7) $>$ (8) $=$ (9) $<$
(Course 2) Q1 For A $\sim$ K in the following sentences, choose the correct answer from among choices (0) $\sim$ (9) below. (1) Consider the quadratic function $$y = a x ^ { 2 } + b x + c$$ whose graph is as shown in the figure at the right. Then $a , b$ and $c$ satisfy the following expressions: (i) $a \mathbf { A } 0 , b \mathbf { B } 0 , c \mathbf { C } 0$; (ii) $a + b + c \mathbf { D } 0$; (iii) $a - b + c \mathbf { E } 0$; (iv) $4 a + 2 b + c \mathbf { F } 0$; (v) $b ^ { 2 } - 4 a c \mathbf { G } 0$. (2) Given the condition that $a , b$ and $c$ satisfy (i) and (ii) in (1), consider the case where the value of $a ^ { 2 } - 8 b - 8 c$ is minimized. We see that $a = \mathbf { H }$. When we express $y = a x ^ { 2 } + b x + c$ in terms of $b$, we have $$y = \mathbf { H } x ^ { 2 } + b x - b + \mathbf { I } \text {. }$$ Also, we see that the range of the values of $b$ is $\mathbf { J } < b < \mathbf { K }$. (0) 0 (1) 1 (2) 2 (3) 3 (4) 4 (5) - 2 (6) - 4 (7) $>$ (8) $=$ (9) $<$
$\mathrm { f } ( x )$ is a polynomial function defined for all real $x$. Which of the following is a necessary condition for the inequality $$\frac { \mathrm { f } ( a ) + \mathrm { f } ( b ) } { 2 } \geq \mathrm { f } \left( \frac { a + b } { 2 } \right)$$ to be true for all real numbers $a$ and $b$ with $a < b$ ?
Here is an attempt to solve the inequality $x ^ { 4 } - 2 x ^ { 2 } - 3 < 0$ by completing the square: $$x ^ { 4 } - 2 x ^ { 2 } - 3 < 0$$ I if and only if $x ^ { 4 } - 2 x ^ { 2 } + 1 < 4$ II if and only if $\left( x ^ { 2 } - 1 \right) ^ { 2 } < 4$ III if and only if $- 2 < x ^ { 2 } - 1 < 2$ IV if and only if $x ^ { 2 } - 1 < 2$ V if and only if $x ^ { 2 } < 3$ VI if and only if $- \sqrt { 3 } < x < \sqrt { 3 }$ Which of the following statements is true? A The argument is completely correct. B The first error occurs in line I. C The first error occurs in line II. D The first error occurs in line III. E The first error occurs in line IV. F The first error occurs in line V. G The first error occurs in line VI.
Where $a, b$ and $c$ are real numbers, $$y = ax^2 + bx + c$$ the parabola intersects the line $y = 1$ at points B and C, and intersects the line $y = 6$ at only point A. The locations of points A, B and C in the rectangular coordinate plane are shown in the figure below. Accordingly, what are the signs of the numbers $a$, $b$ and $c$ respectively? A) +, -, - B) +, +, - C) -, +, + D) -, -, + E) -, -, -