Bài 5:

a: 2x-(3-5x)=4(x+3)

=>2x-3+5x=4x+12

=>7x-3=4x+12

=>3x=15

=>x=5

b: =>5/3x-2/3+x=1+5/2-3/2x

=>25/6x=25/6

=>x=1

c: 3x-2=2x-3

=>3x-2x=-3+2

=>x=-1

d: =>2u+27=4u+27

=>u=0

e: =>5-x+6=12-8x

=>-x+11=12-8x

=>7x=1

=>x=1/7

f: =>-90+12x=-45+6x

=>12x-90=6x-45

=>6x-45=0

=>x=9/2

ê, tưng câu 1 thôi

đăng từng câu 1 thôi

1)

\(\Leftrightarrow\dfrac{3-2x}{5}-\dfrac{2-x}{3}>0\)

\(\dfrac{9-6x}{15}-\dfrac{10-5x}{15}>0\)

\(\Leftrightarrow9-6x-10+5x>0\)

\(\Leftrightarrow-x-1>0\)

=> -x > 1

=> x > -1

e) Ta có: \(x^2-4x+5=0\)

\(\Leftrightarrow\left(x-2\right)^2+1=0\)(Vô lý)

f) Ta có: \(x\left(x-2\right)+x-2=0\)

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

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

g) Ta có: 5x(x-3)-x+3=0

\(\Leftrightarrow\left(x-3\right)\left(5x-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=\dfrac{1}{5}\end{matrix}\right.\)

h) Ta có: \(x^3-\dfrac{1}{4}x=0\)

\(\Leftrightarrow x\left(x-\dfrac{1}{2}\right)\left(x+\dfrac{1}{2}\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{1}{2}\\x=-\dfrac{1}{2}\end{matrix}\right.\)

i) Ta có: \(x^2\left(x-3\right)-4x+12=0\)

\(\Leftrightarrow\left(x-3\right)\left(x-2\right)\left(x+2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=2\\x=-2\end{matrix}\right.\)

e) Cho \(đa\) \(thức\) \(x^2-4x+5=0\)

\(Ta\) \(có\) \(x^2-4+5=0\)

\(x^2-4=0+5\)

\(x^2-4=5\)

\(x^2=5+4\)

\(x^2=9\)

\(\Rightarrow x=\pm3\)

\(Vậy\) \(nghiệm\) \(của\) \(đa\) \(thức\) \(x^2-4x+5\) \(là \) \(0\)

`(1+2cosx)(3-cosx)=0`

\(\Leftrightarrow\left[{}\begin{matrix}cosx=-\dfrac{1}{2}\\cosx=3\left(L\right)\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{2\pi}{3}+k2\pi\\x=\dfrac{-2\pi}{3}+k2\pi\end{matrix}\right.\\ \Leftrightarrow x=\dfrac{2\pi}{3}+k\pi\)

`(k \in ZZ)`

\(\Leftrightarrow\left[{}\begin{matrix}1+2\cos x=0\\3-\cos x=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}\cos x=-\dfrac{1}{2}\\\cos x=3\end{matrix}\right.\)

Mà \(-1\le\cos x\le1\)

\(\Rightarrow\cos x=-\dfrac{1}{2}\)

\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{2}{3}\pi+k2\pi\\x=\dfrac{4}{3}\pi+k2\pi\end{matrix}\right.\)

Vậy ...

C VÀ A

a.meets  b.loughs  c.opens  d.stops ( gạch chân s )

a.wanted  b.looked  c.placed  d.asked ( gạch chân ed )

a.meets /s/  b.loughs /s/ c.opens /z/        d.stops /s/ ( gạch chân s )

a.wanted /id/       b.looked /t/      c.placed /t/        d.asked /t/ ( gạch chân ed )

5. 

ĐKXĐ: \(cos\left(x-30^0\right)\ne0\Leftrightarrow x\ne120^0+k180^0\)

Pt tương đương:

\(\left[{}\begin{matrix}tan\left(x-30^0\right)=0\\cos\left(2x-150^0\right)=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x-30^0=k180^0\\2x-150^0=90^0+k180^0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=30^0+k180^0\\x=120^0+k90^0\end{matrix}\right.\)

Kết hợp ĐKXĐ: \(\Rightarrow x=30^0+k180^0\)

6.

\(\Leftrightarrow2\sqrt{2}sinx.cosx+2cosx=0\)

\(\Leftrightarrow2cosx\left(\sqrt{2}sinx+1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}cosx=0\\sinx=-\dfrac{\sqrt{2}}{2}\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{\pi}{2}+k\pi\\x=-\dfrac{\pi}{4}+k2\pi\\x=\dfrac{5\pi}{4}+k2\pi\end{matrix}\right.\)

5. \(\Leftrightarrow\left[{}\begin{matrix}\tan\left(x-30\right)=0\\\cos\left(2x-150\right)=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x-30=360k\\\left[{}\begin{matrix}2x-150=90+360k\\2x-150=270+360k\end{matrix}\right.\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=30+360k\\x=120+180k\\x=210+180k\end{matrix}\right.\)

Vậy ...

6, \(\Leftrightarrow2\sqrt{2}\sin x.\cos x+2\cos x=0\)

\(\Leftrightarrow\cos x\left(1+\sqrt{2}\sin x\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}\cos x=0\\\sqrt{2}\sin x+1=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}\left[{}\begin{matrix}x=\dfrac{\pi}{2}+k2\pi\\x=\dfrac{3}{2}\pi+k2\pi\end{matrix}\right.\\x=-\dfrac{\pi}{4}+k2\pi\\x=\dfrac{7}{4}\pi+k2\pi\end{matrix}\right.\)

Vậy ...

11. How many eggs do you want to buy?

12. How much cheese does your mom want?

13. How many kilos of rice do you want?

14. How many exercises do Minh must finish?

15. Is there any butter in the jar?

16. How many cities and provinces does Viet Nam have?

17. How many pancakes are you making?

18. How many ice-creams does Ha want? 

19. How many eggs do you have in the basket?

20. How many noodles are there in the cupboard?

Em ơi khi đăng bài em đăng 1-2 bài cho một lượt hỏi thui nha!