Kb đi nha
1+1=
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Đổi: 1h30 phút = 1,5h
Quãng đường AB dài là:
60 . 1,5 = 90 (km)
Nửa quãng đường AB dài là:
90 : 2 = 45 (km)
Vận tốc xe máy là:
60 . 3/5 = 36 (km/h)
Xe máy đi hết nửa quãng đường AB trong:
45 : 36 = 1,25 (giờ)
Đáp số 1,25 giờ
Đổi: 1h30 phút = 1,5h
Quãng đường AB dài là:
60 . 1,5 = 90 (km)
Nửa quãng đường AB dài là:
90 : 2 = 45 (km)
Vận tốc xe máy là:
60 . 3/5 = 36 (km/h)
Xe máy đi hết nửa quãng đường AB trong:
45 : 36 = 1,25 (giờ)
Đáp số : 1,25 giờ
Chúc bn hok tốt nha
1+1=3-1=4-2=5-3=6-4=7-5=8-6=9-7=10-8=11-9=12-10=13-11=14-12=15-13=16-14=17-15=18-16=19-17=20-18
Áp dụng bất đẳng thức cô - si ta có:
\(a+b\ge2\sqrt{ab}\)
\(\dfrac{1}{a}+\dfrac{1}{b}\ge\dfrac{2}{\sqrt{ab}}\)
Nhân từng vế của 2 bất đẳng thức trên ta được \(\left(a+b\right)\left(\dfrac{1}{a}+\dfrac{1}{b}\right)\ge4\)
\(\Rightarrow\dfrac{1}{a}+\dfrac{1}{b}\ge\dfrac{4}{a+b}\)
Vậy...
Chứng minh: \(\left(a+b\right)\left(\dfrac{1}{a}+\dfrac{1}{b}\right)\ge4\)
\(\Rightarrow2+\dfrac{a}{b}+\dfrac{b}{a}\ge4\)
\(\Rightarrow2+\dfrac{a}{b}+\dfrac{b}{a}\ge2+2\sqrt{\dfrac{a}{b}.\dfrac{b}{a}}=2+2=4\)
\(\Rightarrow\left(a+b\right)\left(\dfrac{1}{a}+\dfrac{1}{b}\right)\ge4\)
\(\Rightarrow\dfrac{1}{a}+\dfrac{1}{b}\ge\dfrac{4}{a+b}\)
1. Mike can’t buy that car because he doesn’t have enough money.
Mike can’t afford to buy that car_____________.
2. Susan looks forward to see her father soon.
Susan hopes to see her father soon _______________________________________________.
3. She said she didn’t breaking the vase.
aShe denied breaking the vase._______________________________________________.
4. She is thinking about going picnic this weekend.
She is considering going picnic this weekend _______________________________________________.
5. She said she would play badminton with her friends this afternoon.
aShe decided to play badminton with her friends this afternoon. _______________________________________________.
6. She can’t put up with this short of money anymore.
aShe can’t stand this short of money anymore. _______________________________________________.
7. These windows will have to be cleaned again.
aThese windows need to be cleaned again. ____________________________________________.
8. The police told us not to go out of this building.
aThe police warned us not to go out of this building._______________________________________________.
9.She refused to steal the car.
She denied stealing the car _______________________________________________.
10. Manny said he didn’t stole the car, but he said he borrowed it.
Manny denied stealing the car._______________________________________________
1 + 1 = 2 nha !
= 2 đấy bn ạ