Nhờ mn nha
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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
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
chỉ cần cậu tham gia các hoạt động của olm thì sẽ nhận được ngay!
\(\left(x+2\right)\left(\dfrac{360}{x}-6\right)=360\)
\(ĐK:x\ne0\)
\(\Leftrightarrow\left(x+2\right)\left(\dfrac{360-6x}{x}\right)=360\)
\(\Leftrightarrow360-6x+\dfrac{720-12x}{x}=360\)
\(\Leftrightarrow360x-6x^2+720-12x=360x\)
\(\Leftrightarrow6x^2+12x-720=0\)
\(\Delta=12^2-4.6.\left(-720\right)\)
\(=17424>0\)
`->` 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 \(S=\left\{-12;10\right\}\)
`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}`
ĐK : \(x\ne\pm4\)
\(\Leftrightarrow\cdot\dfrac{48\left(x+4\right)+48\left(x-4\right)}{\left(x+4\right)\left(x-4\right)}=\dfrac{5\left(x+4\right)\left(x-4\right)}{\left(x+4\right)\left(x-4\right)}\)
\(\Leftrightarrow48x+192+48x-192==5x^2-80\)
\(\Leftrightarrow96x=5x^2-80\)
\(\Leftrightarrow5x^2-96x-80=0\)
\(\Leftrightarrow5x^2+4x-100-80=0\)
\(\Leftrightarrow4\left(x-20\right)+5x\left(x-20\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-20=0\\5x=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=20\\x=-\dfrac{4}{5}\end{matrix}\right.\)
17.C
18.D
19.B
20.C
21.B