3. Gọi d là ƯCLN(2n + 3, 4n + 8), d ∈ N*

\(\Rightarrow\hept{\begin{cases}2n+3⋮d\\4n+8⋮d\end{cases}\Rightarrow\hept{\begin{cases}2\left(2n+3\right)⋮d\\4n+8⋮d\end{cases}\Rightarrow}\hept{\begin{cases}4n+6⋮d\\4n+8⋮d\end{cases}}}\)

\(\Rightarrow\left(4n+8\right)-\left(4n+6\right)⋮d\)

\(\Rightarrow2⋮d\)

\(\Rightarrow d\in\left\{1;2\right\}\)

Mà 2n + 3 không chia hết cho 2

\(\Rightarrow d=1\)

\(\RightarrowƯCLN\left(2n+3,4n+8\right)=1\)

\(\Rightarrow\frac{2n+3}{4n+8}\) là phân số tối giản.

a) \(\dfrac{\left(-1997\right).1996+1}{\left(-1995\right).\left(-1997\right)+1996}=\dfrac{-1997\left(1995+1\right)+1}{1995.1997+1996}\)

\(=\dfrac{-1997.1995+\left(-1997\right)+1}{1995.1997+1996}=\dfrac{-1997.1995+\left(-1996\right)}{1995.1997+1996}=-1\)

giúp mik đi nhé 

mik đang cần gấp nèeee

a,-7/12

b,5/14

c,-3/8

d,-1

,

,,,,,,,,,ư

\(a,\dfrac{2929-101}{2.1919+404}=\dfrac{29.101-101.1}{2.19.101+4.101}\)

\(=\dfrac{101\left(29-1\right)}{101\left(2.19+4\right)}\)

\(=\dfrac{101.29}{101.42}\)

\(=\dfrac{28}{42}=\dfrac{2}{3}\)

\(b,\dfrac{\left(-5\right)^3.40.4^3}{135.\left(-2\right)^{14}.\left(-100\right)^0}=\dfrac{\left(-5\right)^3.40.4^3}{135.\left(-2\right)^{14}}\)

\(=\dfrac{40.\left(-15\right).64}{135.\left(-2\right)^{14}}\)

\(=\dfrac{5.8.3.\left(-5\right).64}{5.3.9.\left(-2\right)^{14}}\)

\(=\dfrac{8.\left(-5\right).\left(-2\right)^6}{9.\left(-2\right)^{14}}\)

\(=\dfrac{\left(-2\right)^3.5}{9.\left(-2\right)^8}=\dfrac{5}{9.\left(-2\right)^5}\)

\(\dfrac{\left(-5\right)^3.40.4^3}{135.\left(-2\right)^{14}.\left(-100\right)^0}=\dfrac{\left(-5\right)^3.40.4^3}{135.\left(-2\right)^{14}.1}=\dfrac{\left(-15\right).40.64}{135.\left(-2\right)^{14}}=\dfrac{\left(-5\right).3.5.8.64}{15.9.\left(-2\right)^{14}}=\dfrac{8.\left(-5\right).\left(-2\right)^6}{9.\left(-2\right)^{14}}=\dfrac{\left(-2\right)^3.5}{9.\left(-2\right)^8}=\dfrac{5}{9.\left(-2\right)^5}\)

\(\frac{\left(-5\right)^3.40.4^3}{135.\left(-2\right)^{14}.\left(-100\right)^0}=\frac{\left(-5\right)^3.40.4^3}{5.27.4^7}=\frac{\left(-5\right)^3.2}{3^3.4^3}=\frac{\left(-5\right)^3}{3^3.2^5}\)

có gì sai bỏ qua

a) = -320000/2211840 = -125/864

= ((-5)^3 . 5 . 2^3 . 2^6] / ( 5. 3^3 . 2^14 .1)

= ( (-5