gaokao 2019 Q5

gaokao · China · beijing-science 5 marks Inequalities Linear Programming (Optimize Objective over Linear Constraints)

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

The graph of the function $f ( x ) = \frac { \sin x + x } { \cos x + x ^ { 2 } }$ on $[ - \pi , \pi ]$ is approximately

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