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18 tháng 11 2021

17.C

18.D

19.B

20.C

21.B

5 tháng 11 2021

2 she had got the price of the contest, she would be happy now

3 I had gone to the concert last night ,I would be tired

4 John had finished all his homework, he could see a movie now

5 we had listened to my mother, we wouldn't be in trouble right now

Ex5

1 you arrive at the offcie earlier than I do, please turn on the air-conditioner

2 Were it not snowy, the children would go to school

3 he not died so young, he would be a famous musician

4 Were I you, I would take care of my car

5 not very bad-tempered, his wife would give him soon are marrage

6 Had she not got married at such an early age, he would be at university

14 tháng 10 2021

Cảm ơn bạn nha

Ta có: \(\dfrac{x+1}{29}+\dfrac{x+3}{27}=\dfrac{x-3}{33}+\dfrac{x-7}{37}\)

\(\Leftrightarrow\dfrac{x+30}{29}+\dfrac{x+30}{27}-\dfrac{x+30}{33}-\dfrac{x+30}{37}=0\)

\(\Leftrightarrow x+30=0\)

hay x=-30

25 tháng 7 2021

Cám mơn bn nhìu

30 tháng 11 2023

chỉ cần cậu tham gia các hoạt động của olm thì sẽ nhận được ngay!

30 tháng 11 2023

1000000000000000000000000000000000000gp

 

27 tháng 5 2022

\(\left(x+2\right)\left(\dfrac{360}{x}-6\right)=360\)

\(ĐK:x\ne0\)

\(\Leftrightarrow\left(x+2\right)\left(\dfrac{360-6x}{x}\right)=360\)

\(\Leftrightarrow360-6x+\dfrac{720-12x}{x}=360\)

\(\Leftrightarrow360x-6x^2+720-12x=360x\)

\(\Leftrightarrow6x^2+12x-720=0\)

\(\Delta=12^2-4.6.\left(-720\right)\)

    \(=17424>0\)

`->` pt có 2 nghiệm

\(\left\{{}\begin{matrix}x_1=\dfrac{-12-\sqrt{17424}}{12}=-12\\x_2=\dfrac{-12+\sqrt{17424}}{12}=10\end{matrix}\right.\) ( tm )

Vậy \(S=\left\{-12;10\right\}\)

27 tháng 5 2022

`48/[x+4]+48/[x-4]=5`           `ĐK: x \ne +-4`

`<=>[48(x-4)+48(x+4)]/[(x-4)(x+4)]=[5(x+4)(x-4)]/[(x-4)(x+4)]`

   `=>48x-192+48x+192=5x^2-80`

`<=>5x^2-96x-80=0`

`<=>5x^2-100+4x-80=0`

`<=>5x(x-20)+4(x-20)=0`

`<=>(x-20)(5x+4)=0`

`<=>` $\left[\begin{matrix} x=20\\ x=\dfrac{-4}{5}\end{matrix}\right.$   (t/m)

Vậy `S={-4/5;20}`

27 tháng 5 2022

ĐK : \(x\ne\pm4\)

\(\Leftrightarrow\cdot\dfrac{48\left(x+4\right)+48\left(x-4\right)}{\left(x+4\right)\left(x-4\right)}=\dfrac{5\left(x+4\right)\left(x-4\right)}{\left(x+4\right)\left(x-4\right)}\)

\(\Leftrightarrow48x+192+48x-192==5x^2-80\)

\(\Leftrightarrow96x=5x^2-80\)

\(\Leftrightarrow5x^2-96x-80=0\)

\(\Leftrightarrow5x^2+4x-100-80=0\)

\(\Leftrightarrow4\left(x-20\right)+5x\left(x-20\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-20=0\\5x=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=20\\x=-\dfrac{4}{5}\end{matrix}\right.\)