Bài 1: 

a. $\frac{x}{2}=\frac{3,6}{1,2}=3$

$x=3.2=6$

b. 

$\frac{8}{2x+1}=\frac{4}{3}$

$2x+1=\frac{8.3}{4}=6$

$2x=6-1=5$

$x=\frac{5}{2}$

c. $\frac{x}{4}=\frac{9}{x}$

$x^2=9.4=36=6^2=(-6)^2$

$\Rightarrow x=\pm 6$

d.

$\frac{x+1}{2}=\frac{32}{x+1}$

$(x+1)^2=32.2=64=8^2=(-8)^2$

$\Rightarrow x+1=8$ hoặc $x+1=-8$

$\Rightarrow x=7$ hoặc $x=-9$

\(\frac{2^{50}.3^{61}+2^{90}.3^{16}}{2^{51}.3^{61}+2^{31}.3^{61}}\)

\(=\frac{3^{61}\left(2^{50}+2^{90}\right)}{3^{61}\left(2^{51}+2^{31}\right)}\)

\(=\frac{2^{50}+2^{90}}{2^{51}+2^{31}}\)

\(=\frac{2^{31}\left(2^{19}+2^{59}\right)}{2^{31}\left(1+2^{20}\right)}\)

\(=\frac{2^{19}+2^{59}}{1+2^{20}}\)

= ???????? 

:3

a) \(\frac{3x+2}{-4x+5}=-\frac{4}{3}\left(ĐKXĐ:x\ne\frac{5}{4}\right)\)
\(\Rightarrow3\left(3x+2\right)=-4\left(-4x+5\right)\)
\(\Leftrightarrow9x+6=16x-20\)
\(\Leftrightarrow7x=26\)
\(\Leftrightarrow x=\frac{26}{7}\)
b) \(\frac{2\left|x\right|+5}{-4x+3}=-\frac{5}{4}\)(Thôi bài sau tự tìm đkxđ nhá)
\(\Rightarrow8\left|x\right|+20=20x-15\)
\(\Leftrightarrow8\left|x\right|-20x+35\)\(\left(1\right)\)
TH1: Nếu \(x\ge0\)thì \(\left(1\right)\Leftrightarrow8x-20x+35=0\Leftrightarrow x=\frac{35}{12}\left(tm\right)\)
TH2: Nếu \(x< 0\)thì \(\left(1\right)\Leftrightarrow-8x-20x+35=0\Leftrightarrow x=\frac{35}{28}\left(ktm\right)\)
Vậy x=35/12
c)\(\frac{2x+1}{5}=\frac{3}{2x-1}\)
\(\Rightarrow4x^2-1=15\)
\(\Leftrightarrow4x^2=16\)
\(\Leftrightarrow x^2=4\)
\(\Leftrightarrow\orbr{\begin{cases}x=2\\x=-2\end{cases}}\)
d)\(\frac{x+1}{2x+1}=\frac{0,5x+2}{x+3}\)
\(\Leftrightarrow\left(x+1\right)\left(x+3\right)=\left(2x+1\right)\left(0,5x+2\right)\)
\(\Leftrightarrow x^2+4x+3=x^2+4,5x+2\)
\(\Leftrightarrow0,5x=1\)
\(\Leftrightarrow x=2\)
e) \(\frac{\left|6x+1\right|}{4}=\frac{2}{4}\)
\(\Leftrightarrow\left|6x+1\right|=2\)
\(\Leftrightarrow\orbr{\begin{cases}6x+1=2\\6x+1=-2\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{1}{6}\\x=-\frac{1}{2}\end{cases}}}\)
g)\(\frac{\left|3x-5\right|}{3}=\frac{\left|x\right|}{2}\)
\(\Leftrightarrow\frac{\left|3x-5\right|}{\left|x\right|}=\frac{3}{4}\)
\(\Leftrightarrow\left|\frac{3x-5}{x}\right|=\frac{3}{4}\)
\(\Leftrightarrow\orbr{\begin{cases}\frac{3x-5}{x}=\frac{3}{4}\\\frac{3x-5}{x}=-\frac{3}{4}\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{20}{9}\\x=\frac{4}{3}\end{cases}}}\)
Mỏi tay quá, xin tý cho sảng khoái nào!!
\(\)

Hôm nay tặng bn 3 k , ngày mai mk tặng tiếp 3 k nx nhé ^^ Thanks bn nhiều lắm !

Cô chào em, chúc em 1 buổi tối vui vẻ bên gia đình! ^^

hòi cô phải giáo viên ko vậy ạ

hi bn

"Thế giới ảo có hàng triệu người, sao bạn lại vinh dự nhận được lời chào từ mình nhỉ?"

chào bạn nha

Ta có:

9⁷ + 81⁴ - 27⁵

= (3²)⁷ + (3⁴)⁴ - (3³)⁵

= 3¹⁴ + 3¹⁶ - 3¹⁵

= 3¹⁴.(1 + 3² - 3)

= 3¹⁴.(1 + 9 - 3)

= 3¹⁴.7 chia hết cho 7 (đpcm)

Ta có:

87\(.\overline{ab}=\overline{3ab3}\)

\(\Rightarrow87.\overline{ab}=\overline{3ab0}+3\)

\(\Rightarrow87.\overline{ab}=\overline{3ab}.10+3\)

\(\Rightarrow87.\overline{ab}=\left(300+\overline{ab}\right).10+3\)

\(\Rightarrow87.\overline{ab}=3000+3+\overline{ab}.10\)

\(\Rightarrow87.\overline{ab}-\overline{ab}.10=3003\)

\(\Rightarrow77.\overline{ab}=3003\)

\(\Rightarrow\overline{ab}=3003:77\)

\(\Rightarrow\overline{ab}=39\)

đúng ko zậy