Câu 14 làm sao v ạ.
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Câu 24:
Để phương trình có hai nghiệm trái dấu thì \(\left(m^2+2020\right)\left(m-2021\right)< 0\)
=>m<2021
mà m nguyên dương
nên \(m\in\left\{1;...;2020\right\}\)
=>có 2020 số
the blind
Vì the + adj để chỉ 1 nhóm người. VD: the rich là người giàu
Pt bậc 2 có 2 nghiệm trái dấu khi \(ac< 0\)
\(\Leftrightarrow\left(m^2-4\right)m< 0\)
\(\Leftrightarrow m\in\left(-\infty;-2\right)\cup\left(0;2\right)\)
Câu 2 : B (vik T + X luôn = 50% nên lấy 50% - T -> X và G)
Câu 3 : B (vik A + G = 50% mak A = 4G thik thay vào lak tính đc A vs G)
Câu 4 : A (vik A - X = 12.5% mak A + X = 50%,giải hệ lak tìm đc A vs X)
7 Tim told me if I didn't have a degree, I couldn't get a job easily
8 I told Martin he could sleep well at night, if he didn't drink too much coffee
9 Jim told Daise unless she chooses the words more carefully, she would be introuble
10 I said to Dick I would forget Ann's birthday if he didn't remind me
11 Jim told Jane he wouldn't have been late for his intervire if he hadn't missed the train
12 I told my friends if it didn't rain that morning, we could go for a picnic
13 I said if Linda had been at home the day before, I could have visited her
14 They said if the weather were nice that day, they would go to the zoo
Lý thuyết: \(\left(\overrightarrow{a};\overrightarrow{b}\right)=180^0-\left(-\overrightarrow{a};\overrightarrow{b}\right)\)
Ta có: \(\left(\overrightarrow{CA};\overrightarrow{CB}\right)=\widehat{C}=40^0\Rightarrow\left(\overrightarrow{AC};\overrightarrow{CB}\right)=180^0-40^0=140^0\)