Question

Answer 1

 Câu 11:

\(2x+y-3>0\\ \Leftrightarrow2x>3-y\\ Thay.x=-1\Rightarrow2.\left(-1\right)>3-y\Leftrightarrow3-y< -2\Leftrightarrow y>5\\ Vậy:A,D.loại\\ Thay.x=1\Rightarrow2.1>3-y\Leftrightarrow3-y< 2\Leftrightarrow y>3-2\Leftrightarrow y>1\\ Vì:\dfrac{3}{2}>1\Rightarrow Chọn.B\)

Answer 2

Câu 9:

\(x-4y+5\ge0\\ \Leftrightarrow x\ge4y-5\\ TH1:y=0\Rightarrow x\ge-5\Rightarrow A.đúng\\ TH2:y=1\Rightarrow x\ge-1\Rightarrow B.sai\\ TH3:y=-3\Rightarrow x\ge-17\Rightarrow C.đúng\\ TH4:y=0\Rightarrow x\ge-5\Rightarrow D.đúng\\ Chọn.B\)

Answer 3

Câu 8:

\(Câu.8:\\Ta.có:2x+y< 1\Rightarrow y< 1-2x\\ TH1:x=-2\Rightarrow y< 5\Rightarrow A.dúng\\ TH2:x=3\Rightarrow y< -5\Rightarrow B.đúng\\ TH3:x=0\Rightarrow y< 1\Rightarrow C.sai\left(Do:y_{câu.C}=1\right)\\ TH4:Đúng\left(Do:y< 1\right)\Rightarrow D.đúng\\ Chọn.C\)

Answer 4

\(Câu.7:\\ 5\left(x+2\right)-9< 2x-2y+7\Leftrightarrow5x-2x< 7+9-2y-10\\ \Leftrightarrow3x< 6-2y\\ \Leftrightarrow x< 3-\dfrac{2}{3}y\\ TH1:y=1\Rightarrow x< \dfrac{7}{3}\Rightarrow A.đúng\left(Do:-2< \dfrac{7}{3}\right)\\ TH2:y=3\Rightarrow x< 1\Rightarrow B.sai\left(Do:2>1\right)\\ TH3:y=-1\Rightarrow x< \dfrac{11}{3}\Rightarrow C.đúng\left(Do:2< \dfrac{11}{3}\right)\\ TH4:y=0\Rightarrow x< 3\Rightarrow D.đúng\left(Do:0< 3\right)\\ Chọn.B\)

Answer 5

Câu 10:

A. Bpt bậc nhất 3 ẩn

B. Bpt bậc hai 1 ẩn

C. Bpt bậc hai 2 ẩn

D. Bpt bậc nhất 2 ẩn

Chọn D

Answer 6

\(Câu.5:\\ 4\left(x-1\right)+5\left(y-4\right)>2x-9\\ \Leftrightarrow4x-2x>4+20-9-5y\\ \Leftrightarrow2x>15-5y\\ \Leftrightarrow x>\dfrac{15}{2}-\dfrac{5}{2}y\\ TH1:y=0\Rightarrow x>\dfrac{15}{2}\Rightarrow A.sai\left(Do:0< \dfrac{15}{2}\right)\\ TH2:y=1\Rightarrow x>5\Rightarrow B.sai\left(Do:1< 5\right)\\ TH3:C.sai\left(Do:-1< 5\right)\\ TH4:y=5\Rightarrow x>-5\Rightarrow D.đúng\left(Do:2>-5\right)\\ Chọn.D\)

Answer 7

\(Câu.6:\\ 3x+2\left(y+3\right)>4\left(x+1\right)-y+3\\ \Leftrightarrow4x-3x< 2y+6-4+y-3\\ \Leftrightarrow x< 3y-1\\ TH1:y=0\Rightarrow x< -1\Rightarrow A.sai\left(Do:3>-1\right)\\ TH2:y=1\Rightarrow x< 2\Rightarrow B.sai\left(Do:3>2\right)\\ TH3:C.đúng\left(Do:1< 2\right)\\ TH4:D.sai\left(Do:0>-1\right)\\ Vậy.chọn.C\)