\(9.3^x=3^{2021}:3^{2019}\)

\(9.3^x=3^2\)

\(3^x=9:9\)

\(3^x=1\)

\(3^x=3^0\)

\(x=0\)

\(2\left(5x-2\right)^4-12=150\)

\(2\left(5x-2\right)^4=162\)

\(\left(5x-2\right)^4=81\)

\(\left(5x-2\right)^4=\pm3^4\)

\(\Rightarrow\hept{\begin{cases}5x-2=3\\5x-2=\left(-3\right)\end{cases}}\Rightarrow\hept{\begin{cases}x=1\\x=-\frac{1}{5}\end{cases}}\)

Vậy ... 

TL:

là sao cj

í cj là sao ạ

  -HT-

iem ko hỉu :)??????

38 - 2 . ( 3x - 1 ) = 10

=> 6x - 2 = 28

=> 6x = 30

=> x = 5

Vậy x = 5

Gọi ƯCLN( 15n + 6 , 9n + 3 ) = d

\(\Rightarrow\hept{\begin{cases}15n+6⁝d\\9n+3⁝d\end{cases}}\Rightarrow\hept{\begin{cases}45n+18⁝d\\45n+15⁝d\end{cases}}\Rightarrow\left(45n+18\right)-\left(45n+15\right)⁝d\)

\(\Rightarrow3⁝d\)mà \(\hept{\begin{cases}15n+6=3.\left(5+2\right)⁝3\\9n+3=3.\left(3n+1\right)⁝3\end{cases}}\)=> d = 3

15(x+1) +35=2.10^2

15(x+1)= 200 -35=165

x+1=165:15=11

x=11-1=10. Vậy x=10 (Dạng Toán lớp 2)

\(3x+xy+y+3=22+3\)

\(3\left(x+1\right)+y\left(x+1\right)=25\)

\(\left(3+y\right)\left(x+1\right)=25\)

\(\Rightarrow3+y;x+1\in\text{Ư}\left(25\right)\)

Bạn tự lập bảng rồi làm nhé 

\(3^4-5.4^2\)

\(=81-5.16\)

\(=81-80=1\)

\(63.73-27.63+37.73-27.37\)

\(=63.\left(73-27\right)+37.\left(73-27\right)\)

\(=63.46+37.46\)

\(=\left(63+37\right).46\)

\(=100.46=4600\)

2 câu ạ