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(5/2*x-3)/15=3/10

5/2*x-3=3/10*15

5/2*x-3=9/2

5/2*x=9/2+3=9/2+6/2

5/2*x=15/2

x=15/2:5/2

x=3

Tính nhanh 2×(15-5)+3×10-5×10 

Ai nhanh mk tick ✔

P = 3 . (-2)³ - (-2)

P = 3 . (-6) + 2

P = -18 +2

P = -16

Câu 1: She doesn't live in London because she doesn't know anyone there

->She'd.....live in London if she knew anyone there ......................................................................................................

Câu 2: I can't live in the country because I can't find a job there

->I'd...........live in the country if I could find a job there..............................................................................

Câu 3: I don't have a spare ticket. I can;t take you to the concert

->If I.........had a spare ticket, I could take you to the concert.................................

Câu 4: The schoolchildren sowed some seed, but they forgot to water them so they didn't go

-> If the children .....hadn't forgot to water the seeds, they would have grown................................

Câu 5: They don't understand a problem. They won't find a solution

-> If they...

Câu 6:He sit too much. He isn't fit

-> If he........didn't sit too much, he would be fit.....

ảnh nhỏ quá bạn

Câu 1: She doesn't live in London because she doesn't know anyone there

->She'd...........................................................................................................

Câu 2: I can't live in the country because I can't find a job there

->I'd..........................................................................................

Câu 3: I don't have a spare ticket. I can;t take you to the concert

->If I..........................................

Câu 4: The schoolchildren sowed some seed, but they forgot to water them so they didn't go

-> If the children .....................................

Câu 5: They don't understand a problem. They won't find a solution

-> If they...

Câu 6:He sit too much. He isn't fit

-> If he.............

Bài 1 :

Gọi tử số là x => Mẫu số là x - 8

Nếu thêm tử hai đơn vị thì tử mới là : \(x+2\)

Nếu bớt mẫu 3 đơn vị thì mẫu mới là : \(x-11\)

Mà phân số mới là \(\dfrac{3}{4}.\)

Theo đề bài , ta có phương trình :

\(\dfrac{x+2}{x-11}=\dfrac{3}{4}\)

\(\Leftrightarrow4\left(x+2\right)=3\left(x-11\right)\)

\(\Leftrightarrow4x+8=3x-33\)

\(\Leftrightarrow x=-41\)

Vậy tử là -41

mẫu là -49

Bài 3 : \(\dfrac{x-1}{4}+1\ge\dfrac{x+1}{3}\)

\(\Leftrightarrow\dfrac{3\left(x-1\right)}{12}+\dfrac{12}{12}\ge\dfrac{4\left(x+1\right)}{12}\)

\(\Leftrightarrow3x-3+12\ge4x+4\)

\(\Leftrightarrow-x\ge-5\)

\(\Leftrightarrow x\le5\)

Vậy...............

Câu 4) \(\dfrac{2x+1}{x-1}=\dfrac{5\left(x-1\right)}{\left(x+1\right)}\) ( 1 )

ĐKXĐ : \(x\ne1;x\ne-1\)

\(\left(1\right)\Rightarrow\left(2x+1\right)\left(x+1\right)=5\left(x-1\right)\left(x-1\right)\)

\(\Leftrightarrow2x^2+2x+x+1=5\left(x^2-2x+1\right)\)

\(\Leftrightarrow-3x^2+13x-4=0\)

\(\Leftrightarrow\left[{}\begin{matrix}3x-1=0\\x-4=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{3}\\x=4\end{matrix}\right.\left(TMĐKCĐ\right)\)

Vậy ........

b ) \(x^2-3x+2=0\)

\(\Leftrightarrow x^2-x-2x+2\)

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

\(\Leftrightarrow\left(x-2\right)\left(x-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=1\end{matrix}\right.\)

Vậy..........

Câu c và Bài 2 tự làm đi nha lazy quá với lại nó easy . Tự làm đi trình độ đó tới giờ thì cậu chắc chắc phải biết chứ :D

bài 5
góc BAb=180⁰-120⁰=60⁰
mà B1=góc BAb=60⁰(so le trong)
bài 7
có góc BDC=180⁰- góc BDb=180⁰-150⁰=30⁰
=>góc BDC= góc aBD
=>a//b
=>A1=góc ACD=70⁰
=>A2=180⁰-ACD=180⁰-70⁰=110⁰

1 Your sister is interested in doing DIY in her free time, isn't she?

2 Unless that girl study harder, she will fail the exam

3 My father has given up smoking since last year

4 Mary wanted to know what Peter would give his brother on his birthday the day after

1. Your sister is interested in doing DIY in her free time, isn't she?

2. Unless that girl studies harder, she'll fail the exam.

3. My father has given up smoking since last year.

4. Mary wanted to know what Peter would give his brother on his birthday the next day.

Hình vẽ : tự vẽ nha 

Sabc = \(\frac{1}{2}AH.BC=\frac{1}{2}BK.AC\)

=> \(AH.BC=AC.BK\)

=> \(\frac{AH}{BK}=\frac{AC}{BC}=\frac{15.6}{12}=\frac{13}{10}\)

=> \(\frac{AC}{13}=\frac{BC}{10}=t\)

=> \(AC=13t;BC=10t\)

Tam giác ABC cân có AH là đg cao => AH là t tuyến => BH = HC = 1/2 BC = 1/2.10t = 5t 

TAm giác AHC vuông tại H , theo py ta go :

 \(AC^2-HC^2=15.6^2\)

=> \(169t^2-25t^2=15.6^2\)

tính ra t thay vào tìm ra BC 

2S_ABC = AH.BC = AC.BK

ð       15,6BC = 12AC

ð       BC = 12/15,6AC

ð       CH = 6/15,6AC

ð       AH² = AC² – HC² = 144/169AC²

ð       AH = 12/13 AC

ð       15,6 = 12/13AC

ð       AC = 16,9

ð       BC = 12/15,6 AC = 13

ticks 1 cái nữa để tròn 1000 với

\(6,\\ a,P=9\left(x^2-2\cdot\dfrac{1}{9}x+\dfrac{1}{81}\right)+\dfrac{26}{9}=9\left(x-\dfrac{1}{9}\right)^2+\dfrac{26}{9}\ge\dfrac{26}{9}\\ P_{min}=\dfrac{26}{9}\Leftrightarrow x-\dfrac{1}{9}=0\Leftrightarrow x=\dfrac{1}{9}\\ b,Q=3\left(x^2-x+\dfrac{1}{4}\right)+\dfrac{1}{4}=3\left(x-\dfrac{1}{2}\right)^2+\dfrac{1}{4}\ge\dfrac{1}{4}\\ Q_{min}=\dfrac{1}{4}\Leftrightarrow x-\dfrac{1}{2}=0\Leftrightarrow x=\dfrac{1}{2}\\ c,R=\left(x^2-2xy+y^2\right)+x^2+1=\left(x-y\right)^2+x^2+1\ge1\\ R_{min}=1\Leftrightarrow\left\{{}\begin{matrix}x-y=0\\x=0\end{matrix}\right.\Leftrightarrow x=y=0\)