lên mạng nhận soạn bài ;những câu hát nghĩa ting là ra ngay ấy mà

Bn tham khảo Link sau nhé : Soạn bài: Ca dao, dân ca những câu hát về tình cảm gia đình | Soạn văn 7 hay nhất tại VietJack

Học tốt nhá 

# MissyGirl #

\(\left(1\frac{2}{3}-2x\right)\left(x+\frac{1}{2}\right)=0\)

\(\Leftrightarrow\left(\frac{5}{3}-2x\right)\left(x+\frac{1}{2}\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}\frac{5}{3}-2x=0\\x+\frac{1}{2}=0\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=\frac{5}{6}\\x=-\frac{1}{2}\end{cases}}\)

(1 2/3-2x).(x+1/2)=0

=(5/3-2x).(x+1/2)=0    <=>   x+1/2=0

=5/3-2x=0       <=>         x=0-1/2

2x=5/3-0          <=>        x=-1/2

2x=5/3

x=5/3÷2

x=5/6

Vậy x€{5/6;-1/2}

k mik nhé

\(\frac{1999}{2000}=1-\frac{1}{2000}\)      (1)

\(\frac{199}{200}=1-\frac{1}{200}\)      (2)

\(\frac{1}{200}>\frac{1}{2000}\)     (3)

\(\left(1\right)\left(2\right)\left(3\right)\Rightarrow\frac{1999}{2000}>\frac{199}{200}\)

\(A=\frac{x^2-10x+36}{x-5}=\frac{x^2-10x+25+9}{x-5}\) \(=\frac{\left(x-5\right)^2+9}{x-5}=x-5+\frac{9}{x-5}\)

để \(A\in Z\)

<=> \(\frac{9}{x-5}\in Z\)mà \(x\in Z\)

=> \(x-5\inƯ\left(9\right)\)

=> \(x-5\in\left(1;-1;3;-3;9;-9\right)\)

=> \(x\in\left(6;4;8;2;14;-4\right)\)

học tốt

Trên tia đối tia DA lấy điểm E sao cho DE = BC.

Góc BDE là góc ngoài của tam giác ABD

\(\Rightarrow\widehat{BDE}=\widehat{ABD}+\widehat{BAD}=40^o+90^o=130^o\)

Xét hai tam giác BDE và DBC.

\(\hept{\begin{cases}\widehat{BDE}=\widehat{DBC}=130^o\\BC=DE\\BDchung\end{cases}\Rightarrow\Delta BDE=\Delta DBC}\)

\(\Rightarrow S_{BDE}=S_{BDC}\)và \(\widehat{DBE}=\widehat{BDC}=20^o\)

Xét tam giác ABE vuông tại A, \(\widehat{ABE}=\widehat{ABD}+\widehat{BDE}=40^o+20^o=60^o\)

là nửa tam giác đều cạnh BE \(\Rightarrow BE=2AB=\frac{2\sqrt{7}}{3}\)cm

Áp dụng đính lí Pytago: 

\(AE=\sqrt{BE^2-AB^2}=\sqrt{\left(\frac{2\sqrt{7}}{3}\right)^2-\left(\frac{\sqrt{7}}{3}\right)^2}=\frac{\sqrt{21}}{3}\)cm

\(S_{ABE}=\frac{AB.AE}{2}=\frac{\sqrt{7}.\sqrt{21}}{3.3.2}=\frac{7\sqrt{3}}{18}cm^2\) \(S_{ABCD}=S_{ABD}+S_{BCD}=S_{ABD}+S_{BDE}=S_{ABE}=\frac{7\sqrt{3}}{18}cm^2\)

Sửa lại \(\widehat{ABE}=\widehat{ABD}+\widehat{DBE}\)

A = -2 ( x - 3y ) - ( -3x + 8y ) -1

A = -2x + 6y + 3x - 8y - 1

A = x - 2y - 1

-3A = -3 ( x - 2y - 1 )

-3A = -3x + 6y + 1

mặt khác ta có : -3x + 1 = -6y ( theo đề bài )

=> -3x + 1 + 6y = 0

=> -3A = 0

mà -3 khác 0 => A = 0

Vậy, A = 0

\(a,\left|3x-1\right|=\left|5-2x\right|\)

\(\Leftrightarrow\orbr{\begin{cases}3x-1=5-2x\\3x-1=2x-5\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}5x=6\\x=-4\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=\frac{6}{5}\\x=-4\end{cases}}\)

b,\(\left|2x-1\right|+x=2\)

\(\Leftrightarrow\left|2x-1\right|=2-x\)

Điều kiện \(2-x\ge0\Leftrightarrow x\le2\)

\(\Rightarrow\orbr{\begin{cases}2x-1=2-x\\2x-1=x-2\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}3x=3\\x=-1\end{cases}\Rightarrow\orbr{\begin{cases}x=1\left(\text{nhận}\right)\\x=-1\left(\text{nhận}\right)\end{cases}}}\)

c.\(A=0,75-\left|x-3,2\right|\)

Vì \(\left|x-3,2\right|\ge0\Rightarrow0,75-\left|x-3,2\right|\le0,75\)

Dấu "=' xảy ra \(\Leftrightarrow x-3,2=0\Leftrightarrow x=3,2\)

Vậy Max A = 0,75 khi x = 3,2

\(d,B=2.\left|x+1,5\right|-3,2\)

Vì 2. |x + 1,5| ≥ 0 => B ≥ -3,2

Dấu " = ' xảy ra khi \(2\left|x+1,5\right|=0\)

\(\Leftrightarrow x+1,5=0\Leftrightarrow x=-1,5\)

Vậy Min B = -3,2 khi x = -1,5

My answer is : B . 2 cm , 4 cm , 6 cm

C is the best answer

1 it is a quarter past ten

   What time is it?

2 we have chemistry on Wednesday and Friday

    When do you have Chemistry?

3 my family has lunch at 11.30

     What time does your family have lunch?

4 they are playing soccer in the stadium

    Where are they playing soccer?

5 Quang is studying math???????? Chỗ gạch chân đâu bạn

6 the children are going to the museum by bus

    How are the children going to the museum?

7 the school library has about two thousand books

      How many books does the school library have?

8 you can find newspapers on the rack near the librarian s desk

      Where can I find newspapers?

1 . What time is it ?

2 . When do you have chemistry ?

3 . When does your family have lunch ?

4 . Where do they play soccer ?

5 . What's Quang doing ?

6 . How do the children go to the museum ?

7 . How many books are there does your school library have ?

8 . Where can I find newspapers ?