mn giúp mk vs, cảm ơn trc ạ
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Bài 1:
\(54\left(\dfrac{km}{h}\right)=15\left(\dfrac{m}{s}\right);9\left(\dfrac{m}{s}\right)=32,4\left(\dfrac{km}{h}\right)\)
Baì 2:
\(t'=s':v'=5:\left(5.3,6\right)=\dfrac{5}{18}h\)
\(\Rightarrow v_{tb}=\dfrac{s'+s''}{t'+t''}=\dfrac{5+3,8}{\dfrac{5}{18}+\left(\dfrac{15}{60}\right)}\simeq16,67\left(\dfrac{km}{h}\right)\)
Câu 2:
\(\Leftrightarrow\left(x+2\right)\left(10x+3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=-\dfrac{3}{10}\end{matrix}\right.\)
\(A1+2=A2\)
\(\overline{A}\) =\(\dfrac{A1\cdot54+\cdot\left(A1+2\right)\cdot46}{100}\)=79.92
\(\Leftrightarrow\)A1=79\(\Rightarrow\)A2=81
1 When do they do their homework?
2 Who came to the party aloe
3 Which blouse do you like
4 How did she feel after she took a nap
5 How long did she talk to him
6 How many cars do your parents have
7 When are they coming to visit you?
8 Who is your brother
9 Why don't you get up early?
10 How often do you have an English class
1 had gone to bed, we watched television
2 had a swim for 5 days
3 met him for 5 months
4 gone to this club since 1999
5 come to this city since July
6 learned French since 2001
7 played chess for 3 years
8 smoked for 5 years
9 there, Jack had left the office
10 I have visited England
11 the first time I have met this lady
12 I was having dinner, the phone rang
13 we arrived there, David had left the party
14 used to wear glasses before
15 ages since we last went to a concert
16 saw her friends when she left for the United states
17 the first time I have stayed in such an expensive hotel