write a letter

Hold on

leave a message

on the phone

send cards

makes call

intention

send a fax

send e-mail

surf the internet

old

learn

another

when

over

of

wear

home

write

visited

am going to wash

am going to learn

are going to take

am not going to have

looked

wanted

helped

washed

studied

invited

tried

solved

asked

liked

1, looked

2, wanted

3, helped

4, washed

5, studied

6, invited

7, tried

8, solved

9, asked

10, liked

1looked

2wanted

3helped

4washed

5studied

6invited

7tried

8solved

9asked

10liked

Chúc em học tốt

1. My father is clever enough to repair his car

2. He wasn't hard-working enough to get good grades

3. The man is not rich enough to buy this bike

4. That house is not big enough for they to live in

5. The weather was bad enough for the singer sing

6. He is weak enought to lift all those suitcases

7. We are going to visit their grandmother next Sunday

4:

a: Xét ΔABC vuông tại A và ΔHBA vuông tại H có

góc B chung

=>ΔABC đồng dạng với ΔHBA

b: AH=căn 9*16=12cm

AC=căn 12^2+16^2=20cm

HK=16*12/20=192/20=9,6cm

5:

a: Xét ΔMNP vuông tại N và ΔMHN vuông tại H có

góc M chung

=>ΔMNP đồng dạng với ΔMHN

b: NH=căn 16*9=12cm

NP=căn 16^2+12^2=20cm

HK=16*12/20=192/20=9,6cm

\(\left\{{}\begin{matrix}2\left(x+y\right)+\sqrt{x+1}=4\\\left(x+y\right)-3\sqrt{x+1}=-5\end{matrix}\right.\left(x\ge-1\right)\)

Đặt \(\left\{{}\begin{matrix}a=x+y\\b=\sqrt{x+1}\end{matrix}\right.\left(b\ge0\right)\)

\(\Rightarrow\left\{{}\begin{matrix}2a+b=4\\a-3b=-5\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}2a+b=4\left(1\right)\\2a-6b=-10\left(2\right)\end{matrix}\right.\)

Lấy \(\left(1\right)-\left(2\right)\Rightarrow7b=14\Rightarrow b=2\Rightarrow2a=4-2=2\Rightarrow a=1\)

\(\Rightarrow\left\{{}\begin{matrix}x+y=1\\\sqrt{x+1}=2\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}y=-2\\x=3\end{matrix}\right.\)

\(ƯCLN\left(3468,1620,2400\right)\)

Ta có: \(3468=2^2.3.17^2\)

           \(1620=2^2.3^4.5\)

            \(2400=2^5.3.5^2\)

\(\RightarrowƯCLN\left(3468,1620,2400\right)=2^2.3.5.17^2=17340\)

Chúc bạn học tốt!

\(3468=2^2.3.17^2\)

\(1620=2^2.3^4.5\)

\(2400=2^5.3.5^2\)

=> ƯCLN(3468,1620,2400) = \(2^2.3=12\)