Linear Programming (Optimize Objective over Linear Constraints)

The question gives a system of linear inequalities in two variables and asks to find the maximum or minimum of a linear objective function z = ax + by.

brazil-enem 2016 Q151 View
A region of a factory must be isolated, as employees are exposed to accident risks there. This region is represented by the gray portion (quadrilateral with area S) in the figure.
So that employees are informed about the location of the isolated area, informational posters will be posted throughout the factory. To create them, a programmer will use software that allows drawing this region from a set of algebraic inequalities.
The inequalities that should be used in the said software for drawing the isolation region are
(A) $3y - x \leq 0 ; 2y - x \geq 0 ; y \leq 8 ; x \leq 9$
(B) $3y - x \leq 0 ; 2y - x \geq 0 ; y \leq 9 ; x \leq 8$
(C) $3y - x \geq 0 ; 2y - x \leq 0 ; y \leq 9 ; x \leq 8$
(D) $4y - 9x \leq 0 ; 8y - 3x \geq 0 ; y \leq 8 ; x \leq 9$
(E) $4y - 9x \leq 0 ; 8y - 3x \geq 0 ; y \leq 9 ; x \leq 8$
gaokao 2015 Q5 View
5. Given that $\mathrm { x } , \mathrm { y }$ satisfy the constraints $\left\{ \begin{array} { c } x - y \geq 0 \\ x + y - 4 \leq 0 \\ y \geq 1 \end{array} \right.$, then the maximum value of $\mathrm { z } = - 2 \mathrm { x } + \mathrm { y }$ is
(A) $- 1$
(B) $- 2$
(C) $- 5$
(D) $1$
gaokao 2015 Q10 5 marks View
If the system of inequalities $\left\{ \begin{array} { c } x + y - 2 \leq 0 \\ x + 2 y - 2 \geq 0 \\ x - y + 2 m \geq 0 \end{array} \right.$ represents a triangular region with area equal to $\frac { 4 } { 3 }$, then the value of $m$ is
(A) $-3$
(B) $1$
(C) $\frac { 4 } { 3 }$
(D) $3$
gaokao 2015 Q5 View
5. If variables $x$ and $y$ satisfy the constraint conditions $\left\{ \begin{array} { l } x + 2 y \geq 0 , \\ x - y \leq 0 , \\ x - 2 y + 2 \geq 0 , \end{array} \right.$ then the minimum value of $z = 2 x - y$ equals
A. $- \frac { 5 } { 2 }$
B. $- 2$
C. $- \frac { 3 } { 2 }$
D. 2
gaokao 2015 Q14 View
14. If $x , y$ satisfy the constraint conditions $\left\{ \begin{array} { c } x + y - 5 \leq 0 \\ 2 x - y - 1 \geq 0 \\ x - 2 y + 1 \leq 0 \end{array} \right.$, then the maximum value of $z = 2 x + y$ is $\_\_\_\_$ .
gaokao 2015 Q14 View
If $\mathrm { x } , \mathrm { y }$ satisfy the constraint conditions $\left\{ \begin{array} { l } x - y + 1 \geqslant 0 , \\ x - 2 y \leqslant 0 , \\ x + 2 y - 2 \leqslant 0 , \end{array} \right.$ then the maximum value of $z = x + y$ is $\_\_\_\_$ .
gaokao 2015 Q2 View
2. Let variables $x , y$ satisfy the constraint conditions $x - 2y \geq 0$, $x \leq 2$, $y \geq 0$. Then the maximum value of the objective function $z = 3x + y$ is
(A) 7
(B) 8
(C) 9
(D) 14
gaokao 2015 Q2 5 marks View
Variables $x, y$ satisfy the constraints $\left\{\begin{array}{c}x + 2 \geq 0, \\ x - y + 3 \geq 0, \\ 2x + y - 3 \leq 0,\end{array}\right.$ then the maximum value of the objective function $Z = x + 6y$ is
(A) 3
(B) 4
(C) 18
(D) 40
gaokao 2017 Q7 5 marks View
Let $x, y$ satisfy the constraint conditions $\left\{ \begin{array}{l} x - y \geq 1 \\ y \geq 0 \end{array} \right.$. Then the maximum value of $z = x + y$ is
A. 0
B. 1
C. 2
D. 3
gaokao 2017 Q14 5 marks View
Let $x$ and $y$ satisfy the constraints $\left\{ \begin{array} { l } x + 2 y \leqslant 1, \\ 2 x + y \geqslant - 1, \\ x - y \leqslant 0, \end{array} \right.$ then the minimum value of $z = 3 x - 2 y$ is \_\_\_\_
gaokao 2017 Q7 View
Let $x, y$ satisfy the linear constraints $\left\{\begin{array}{l} 2x - 3y + 3 \geq 0, \\ y + 3 \geq 0, \\ 3x - 3 \leq 0 \end{array}\right.$ and let $z = 2x + y$. The minimum value of $z$ is
A. $-15$
B. $-9$
C. $1$
D. $9$
gaokao 2018 Q14 5 marks View
If $x , y$ satisfy the constraints $\left\{ \begin{array} { l } x - 2 y - 2 \leq 0 , \\ x - y + 1 \geq 0 , \\ y \leq 0 , \end{array} \right.$ then the maximum value of $z = 3 x + 2 y$ is \_\_\_\_
gaokao 2018 Q13 5 marks View
If $x , y$ satisfy the constraints $\left\{ \begin{array} { l } x - 2 y - 2 \leqslant 0 , \\ x - y + 1 \geqslant 0 , \\ y \leqslant 0 , \end{array} \right.$ then the maximum value of $z = 3 x + 2 y$ is $\_\_\_\_$
gaokao 2018 Q14 5 marks View
Given the constraints $\left\{ \begin{array} { l } x + 2 y - 5 \geq 0 , \\ x - 2 y + 3 \geq 0 , \\ x - 5 \leq 0 , \end{array} \right.$ the minimum value of $z = x + y$ is \_\_\_\_.
gaokao 2018 Q14 5 marks View
If $x , y$ satisfy the constraints $\left\{ \begin{array} { l } x + 2 y - 5 \geqslant 0 , \\ x - 2 y + 3 \geqslant 0 , \\ x - 5 \leqslant 0 , \end{array} \right.$ then the maximum value of $z = x + y$ is $\_\_\_\_$.
gaokao 2019 Q5 5 marks View
If $x , y$ satisfy $| x | \leqslant 1 - y$ and $y \geqslant - 1$, then the maximum value of $3 x + y$ is (A) $- 7$ (B) 1 (C) 5 (D) 7
gaokao 2019 Q13 View
13. If variables $x , y$ satisfy the constraint conditions $\left\{ \begin{array} { l } 2 x + 3 y - 6 \geq 0 , \\ x + y - 3 \leq 0 , \\ y - 2 \leq 0 , \end{array} \right.$ then the maximum value of $z = 3 x - y$ is $\_\_\_\_$ .
gaokao 2019 Q11 View
11. Let the plane region represented by the system of inequalities $\left\{ \begin{array} { l } x + y \geq 6 , \\ 2 x - y \geq 0 \end{array} \right.$ be $D$ . Proposition $p : \exists ( x , y ) \in D , 2 x + y \geq 9$ ; Proposition $q : \forall ( x , y ) \in D , 2 x + y \leq 12$ . Four propositions are given below:
(1) $p \vee q$
(2) $\neg p \vee q$
(3) $p \wedge \neg q$
(4) $\neg p \wedge \neg q$
The numbers of all true propositions among these four are
A. (1)(3)
B. (1)(2)
C. (2)(3)
D. (3)(4)
gaokao 2020 Q13 5 marks View
If $x , y$ satisfy the constraint conditions $\left\{ \begin{array} { l } 2 x + y - 2 \leqslant 0 , \\ x - y - 1 \geqslant 0 , \\ y + 1 \geqslant 0 , \end{array} \right.$ then the maximum value of $z = x + 7 y$ is $\_\_\_\_$
gaokao 2020 Q13 5 marks View
If $x , y$ satisfy the constraints $\left\{ \begin{array} { l } x + y \geqslant 0 , \\ 2 x - y \geqslant 0 , \\ x \leqslant 1 , \end{array} \right.$ then the maximum value of $z = 3 x + 2 y$ is $\_\_\_\_$ .
gaokao 2020 Q13 5 marks View
If $x , y$ satisfy the constraints $\left\{ \begin{array} { l } x + y \geqslant 0 , \\ 2 x - y \geqslant 0 , \\ x \leqslant 1 , \end{array} \right.$ then the maximum value of $z = 3 x + 2 y$ is $\_\_\_\_$ .
gaokao 2020 Q7 5 marks View
Given $\left\{ \begin{array} { l } x + y \geq 2 \\ y \geq 0 \\ x + 2 y - 3 \leq 0 \end{array} \right.$, find the maximum value of $z = y - 2 x$ as $\_\_\_\_$
gaokao 2022 Q5 5 marks View
If $x , y$ satisfy the constraints $\left\{ \begin{array} { l } x + y \geqslant 2 , \\ x + 2 y \leqslant 4 , \end{array} \right.$ then the maximum value of $z = 2 x - y$ is
A. $- 2$
B. 4
C. 8
D. 12
gaokao 2023 Q14 5 marks View
Let $x , y$ satisfy the constraints $\left\{ \begin{array}{l} -2x + 3y \leqslant 3 \\ 3x - 2y \leqslant 3 \\ x + y = 1 \end{array} \right.$ . Let $z = 3x + 2y$ . The maximum value of $z$ is $\_\_\_\_$ .
gaokao 2023 Q14 View
If $x , y$ satisfy the constraints $\left\{ \begin{array} { l } x - 3 y \leqslant - 1 \\ x + 2 y \leqslant 9 \\ 3 x + y \geqslant 7 \end{array} \right.$, then the maximum value of $z = 2 x - y$ is \_\_\_\_