GIÚP MK NHANH Ạ 4: 30 MK CẦN GẤP Ạ
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1 C => hers
2 B => will use
3 D => their
4 A => will be pedaling
5 A => travel
6 C => less
7 D => have they
8 D => than
9 A => worked
10 B => fewer
Câu 15:
Gọi $x_0$ là nghiệm chung của 2 pt thì:
\(\left\{\begin{matrix}
x_0^2+ax_0+1=0\\
x_0^2-x_0-a=0\end{matrix}\right.\Rightarrow x_0(a+1)+(a+1)=0\)
\(\Leftrightarrow (x_0+1)(a+1)=0\)
Hiển nhiên $a\neq -1$ để 2 PT không trùng nhau. Do đó $x_0=-1$ là nghiệm chung của 2 PT
Thay vào:
$(-1)^2+a(-1)+1=0$
$\Leftrightarrow 1-a+1=0\Rightarrow a=2$
Đáp án C.
Câu 16:
D sai. Trong tam giác vuông tại $A$ là $ABC$, $\cos (90^0-\widehat{B})=\cos \widehat{C}$ và không có cơ sở để khẳng định $\cos \widehat{C}=\sin \widehat{C}$
Tìm GTNN của A=\(x^4-6x^3+12x^2-12x+2021\)
Giúp mk vs ạ mk đang cần gấp ai nhanh mk sẽ vote cho ạ :<
\(Sửa:A=x^4-6x^3+13x^2-12x+2021\\ A=\left(x^4-6x^3+9x^2\right)+4\left(x^2-3x\right)+4+2017\\ A=\left(x^2-3x\right)^2+4\left(x^2-3x\right)+4+2017\\ A=\left(x^2-3x+2\right)^2+2017\ge2017\\ A_{min}=2017\Leftrightarrow x^2-3x+2=0\Leftrightarrow\left(x-2\right)\left(x-1\right)=0\Leftrightarrow\left[{}\begin{matrix}x=1\\x=2\end{matrix}\right.\)
6/20:3=6/20x1/3=6/60=1/10
11h-8h30p=2h30p=2.5h
10 7/10-4 3/10
=107/10-43/10
=64/10=32/5
chúc bn học tốt!
3. He hasn't washed the dishes yet.
4. He hasn't watered the plants yet .
5. He has already done the shopping
6. He has already taken the dog for a walk
7. He has already ironed his clothes
8. He has already washed his car
9. He hasn't tidied the kitchen yet
10. He hasn't mended the kettle yet
3. He hasn't washed the dishes yet.
4. He hasn't watered the plants yet .
5. He has already done the shopping
6. He has already taken the dog for a walk
7. He has already ironed his clothes
8. He has already washed his car
9. He hasn't tidied the kitchen yet
10. He hasn't mended the kettle yet
2, existed 5, explored
3, have develop 6 saw
4 ,have found 7 stopped
8, caught 9 have always want
10 haven't think 11 have studied
12 said 13 have bought
14 showed