Câu 1: (-13).(-11)=143

Câu 2 : -170-9+2+1:2+1=-179+2+1/2+1=-176+1/2=-175,5

Câu 3:-2/30-(-20/5)+16/4=-2/30+20/5+16/4=-1/15+4+4=-1/15+8=-1/15+120/15=121/15

(-13).(-11)

=13.11

=143

2.

(-179)-9+2+1:2+1

=(-179)-9+2+0.5+1

=(-188)+2+0.5+1

=(-186)+0.5+1

=(-184.5)

3.

(-2/3)-(-20/5)+16/4

=(-2/3)+20/5+16/4

=-40/60+240/60+240/60

=520/60=26/3

Ta co :

E=\(\frac{2}{2}+\frac{3}{2}+\frac{4}{2}+\frac{5}{2}+...+\frac{201}{2}\)

   =\(\frac{2+3+4+5+...+201}{2}\)

   =\(\frac{\left[\left(201+2\right)\left(201-2\right):1+1\right]:2}{2}\)

   =\(\frac{40398:2}{2}\)

=\(\frac{20199}{2}\)

Đúng thì k không thì giúp tớ với 

kết quả ra sai rồi

\(E=\frac{2+3+4+...+201}{2}=\frac{\frac{\left[\left(201-2\right):1+1\right].\left(201+2\right)}{2}}{2}=\frac{\frac{200.203}{2}}{2}=\frac{100.203}{2}\)=10150

kq=55

=(1+9)+(2+8)+(3+7)+(4+6)+10+5.

=10+10+10+10+10+5=55.

tk mk nha.\chúc các bạn tk mk học giỏi

=(1+9)+(2+8)+(3+7)+(4+6)+10+5

=10+10+10+10+10+5

=55

1.Why/you/want/go/post office

.................Why do you want to go to the post office?.......................

2. We/not go/zoo/Friday.

................We don't go to the zoo on Friday.......................

3. My/birthday/July

.................My birthday is in July.....................

4. There/some/notebook/shelf

............There are some notebooks on the shelf..................

5, I /like/speak/English/well

...............I like to speak English well...............

Why do you want to go to the post office?

We don't go to the zoo on Friday.

My birthday is in July.

There are some notebooks on the shelf.

I like to speak English well.

Câu 1 : 1/3.x + 2/5.x ( x - 1 ) = 0

< = > 1/3.x + 2/5.x - 2/5 = 0

< = > 1/3.x + 2/5.x = 2/5

< = > 11/15 .x = 2/5

< = > x = 2/5 : 11/15 

< = > x = 6/11

Vậy x = 6/11 

Bài mk làm đúng rồi cho mk sửa lại cái đề 1/3.x + 2/5 . ( x - 1 ) = 0

Câu 1 : 1/3 . x + 2/5 . ( x - 1 ) = 0

Câu 2 : 4/x+2 = 5/2.x + 1

Câu 1 : 1/3.x + 2/5.x ( x - 1 ) = 0

< = > 1/3.x + 2/5.x - 2/5 = 0

< = > 1/3.x + 2/5.x = 2/5

< = > 11/15 .x = 2/5

< = > x = 2/5 : 11/15 

< = > x = 6/11

Vậy x = 6/11 

Bài 4: 

b: Xét ΔAHB vuông tại H có HM là đường cao

nên \(AM\cdot AB=AH^2\left(1\right)\)

Xét ΔAHC vuông tại H có HN là đường cao

nên \(AN\cdot AC=AH^2\left(2\right)\)

Từ (1) và (2) suy ra \(AM\cdot AB=AN\cdot AC\)

\(TanB=\dfrac{AC}{AB}\Rightarrow Tan30^o=\dfrac{AC}{4,5}\Rightarrow AC=Tan30^o.4,5=\dfrac{3\sqrt{3}}{2}\left(m\right)\)

\(CosB=\dfrac{AB}{BC}\Rightarrow Cos30^o=\dfrac{4,5}{BC}\Rightarrow BC=Cos30^o.4,5=\dfrac{9\sqrt{3}}{4}\)

Chiều cao ban đầu của cây tre là: \(\dfrac{3\sqrt{3}}{2}+\dfrac{9\sqrt{3}}{4}=\dfrac{15\sqrt{3}}{4}\approx6,5\left(m\right)\)

\(2^3+\left(\dfrac{1}{5}\right)^4+5^4=8+\dfrac{1}{625}+625=\dfrac{5000+1+625^2}{625}=\dfrac{395626}{625}\)

\(Sửa:2^3+\left(\dfrac{1}{5}\right)^4\cdot5^4=8+\left(\dfrac{1}{5}\cdot5\right)^4=8+1=9\)