bài dễ hơn đc ko?

\(\Rightarrow\orbr{\begin{cases}2x+1=12\\y-3=12\end{cases}\Rightarrow\orbr{\begin{cases}2x=12-1\\y=12+3\end{cases}}}\)\(\Rightarrow\orbr{\begin{cases}2x=11\\y=15\end{cases}}\Rightarrow\orbr{\begin{cases}x=11\div2\\y=15\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{11}{2}\\y=15\end{cases}}\)

Vậy \(x,y\in\hept{\begin{cases}\\\end{cases}}\frac{11}{2};15\)

                                                             Bài giải

Ta có : 

\(\left(2x+1\right)\left(y-3\right)=12\)

\(\Rightarrow\text{ }\left(2x+1\right)\text{ ; }\left(y-3\right)\inƯ\left(12\right)\)

Mà \(\left(2x+1\right)\text{ là số lẻ }\Rightarrow\text{ }\left(2x+1\right)\in\left\{-1\text{ ; }1\right\}\)

\(\Rightarrow\text{ }\hept{\begin{cases}2x+1=-1\\y-3=-12\end{cases}}\)                 \(\Rightarrow\hept{\begin{cases}2x=-2\\y=-9\end{cases}}\)          \(\Rightarrow\hept{\begin{cases}x=-1\\y=-9\end{cases}}\)

Hoặc 

\(\Rightarrow\hept{\begin{cases}2x+1=1\\y-3=12\end{cases}}\)                         \(\Rightarrow\hept{\begin{cases}2x=0\\y=15\end{cases}}\)                      \(\Rightarrow\hept{\begin{cases}x=0\\y=15\end{cases}}\)

\(\Rightarrow\text{ }\left(x\text{ ; }y\right)=\left(-1\text{ ; }-9\right),\left(0\text{ ; }15\right)\)

                                                           Bài giải

Ta có : 

\(x\left(y+1\right)=xy+x=40\)

Mà \(xy=2\) \(\Rightarrow\text{ }2+x=40\)

                        \(\Rightarrow\text{ }x=40-2=38\)

Mà  \(xy=2\text{ }\Rightarrow\text{ }38\cdot y=2\text{ }\Rightarrow\text{ }y=\frac{2}{38}=\frac{1}{19}\)

Và \(x>y\left(38>\frac{1}{19}\right)\)

\(\frac{2}{8}+\frac{2}{7}+\frac{1}{4}\)

=\(\frac{14}{56}+\frac{16}{56}+\frac{14}{56}\)

=\(\frac{44}{56}\)

=\(\frac{11}{14}\)

\(\frac{2}{8}+\frac{2}{7}+\frac{1}{4}\)

\(=\left(\frac{2}{8}+\frac{2}{7}\right)+\frac{1}{4}\)

\(=\frac{15}{28}+\frac{1}{4}\)

\(=\frac{11}{14}\)

\(25< x+17< 3\times9\)

\(\Leftrightarrow25< x+17< 27\)

\(\Leftrightarrow x+17=26\)

\(\Leftrightarrow x=26-17\)

\(\Leftrightarrow x=9\)

Ta có : 25 < x + 17 < 3 x 9

= 25 < x + 17 < 27

=> x = { 9 }

Ta có: \(x^5=32\)

\(\Leftrightarrow x^5=2^5\)

\(\Leftrightarrow x=2\)

\(x \)⁵ = 32

=> \(x \)⁵ = 2⁵

=> \(x \) = 2

\(2n+5⋮n+1\)

Ta có: \(\left(n+1\right)⋮\left(n+1\right)\)

\(\Rightarrow2\left(n+1\right)⋮\left(n+1\right)\)

\(\Rightarrow\left(2n+5\right)-\left(2n+2\right)⋮\left(n+1\right)\)

\(\Rightarrow\left(2n+5-2n-2\right)⋮\left(n+1\right)\)

\(\Rightarrow3⋮\left(n+1\right)\)

\(\Rightarrow\left(n+1\right)\inƯ\left(3\right)=\left\{1;3\right\}\)

\(\Rightarrow n\in\left\{0;2\right\}\)

Vậy  \(n\in\left\{0;2\right\}\)

~~~Học Tốt ~~~

Có ai biết ko giúp mình với

\(3x^2-15=93\)

\(\Leftrightarrow3x^2=93+15\)

\(\Leftrightarrow3x^2=108\)

\(\Leftrightarrow x^2=108:36\)

\(\Leftrightarrow x^2=36\)

\(\Leftrightarrow\orbr{\begin{cases}x=6\\x=-6\end{cases}}\)

~~~Học Tốt~~~