3.45

ttttttyyyyyyyyyyyyyyyyyyyyyyyyyyyyyui

số lớn nhất là 33

\(\dfrac{1}{ab}\ge\dfrac{4}{\left(a+b\right)^2}\)
\(\Leftrightarrow4ab\ge\left(a+b\right)^2\)
\(\Leftrightarrow4ab\ge a^2+2ab+b^2\)
\(\Leftrightarrow0\ge a^2+2ab+b^2-4ab\)
\(\Leftrightarrow0\ge a^2-2ab+b^2\)
\(\Leftrightarrow0\ge\left(a-b\right)^2\)
Biểu thức này đúng \(\forall a,b< 0\)
Dấu "=" xảy ra khi \(a=b\)

Bán kính hình tròn là 

r x r = 7,065 : 3,14 = 2,25 => r = 1,5 m

Chu vi hình tròn là :

1,5x2x3,14 = 9,42 (m)

             Đáp số :  9,42 m

200 trong số la mã viết là c nha 

Chu vi bánh xe là :

65x3,14=204,1(m)

Đổi : 2041 m =204100 cm

Để đi được 2041 m thì bánh xe phải lăn :

204100 : 204,1 = 1000 (vòng)

Đáp số : 1000 vòng

1. At last you're here! I(wait)..........have been waiting......... here for more than half an hour!
2. My father(work).......has worked......... in Canada for last year, so by the time he(return)..........returns............ the month after next I(not see).......won't have seen......... him for fourteen months.
3. When you(see)......see....... him again you(be)....will be......surprised to see that his health(improve).....has been improved....... since he(go)........went........ to Switzerland.

ta có: 6-4=2;6+4=10suy ra 6+4=210(theo cách đố trên)

tương tự như z:ta có 7-6=1; 7+6=13suy ra 7+6=113

29/35 

olm duyệt đi

Chia động từ trong ngoặc
1 , I ( go ) ..................go.............. to school everyday.
2 , I ( go ) .................went............... to school yesterday.
3 , She ( play ) ...........plays...........table tennis every afternoon.
4 , She ( play ) ..............played.................. table tennis last week.
5 , Last week I was ten years old but I ..............am....... eleven now.
week -> year
6 , Where ..............were................you at nine o' clock last friday afternoon.
7 , ...................Are.................. you tired now ?
8 , We ( go ) ..................went................. to the beach yesterday.
9 , I ( love ) .............love................. this teddy bear.
10 , Sam ( sell) ..................sold....................... his computer yesterday.