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

Bài 2:

a: Để A là số nguyên thì \(x+3-5⋮x+3\)

\(\Leftrightarrow x+3\in\left\{1;-1;5;-5\right\}\)

hay \(x\in\left\{-2;-4;2;-8\right\}\)

b: Để  B là số nguyên thì \(x^2-1⋮x+1\)

\(\Leftrightarrow\left(x-1\right)\left(x+1\right)⋮x+1\)

hay \(x\ne-1\)

b) \(\dfrac{6\cdot9-2\cdot17}{63\cdot3-119}\)

\(=\dfrac{2\left(3\cdot9-17\right)}{7\cdot\left(3\cdot9-17\right)}\)

\(=\dfrac{2}{7}\)

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

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

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

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

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

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

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

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

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

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

Phân số a quá dễ, bạn chỉ việc giản ước tử với mẫu sẽ được \(\frac{1}{-1995}\)

b) \(\frac{2.3+4.6+14.21}{3.5+6.10+21.35}\)

Sau khi giản ước ta có: 

\(\frac{2+2+2}{5+5+5}=\frac{8}{15}\)

\(\frac{-1997.1996+1}{\left(1996-1\right).1997+1996}=\frac{-1997.1996+1}{1996.1997-1997+1996}=\frac{-\left(1997.1996-1\right)}{1996.1997-1}=-1\)

\(\frac{2.3.\left(1+2.3+7.7\right)}{3.5.\left(1+3.2+7.7\right)}=\frac{2}{5}\)

\(\frac{3.7.13.37.39-10101}{505050-70707}=\frac{10101.39-10101}{10101.50-10101.7}=\frac{10101.\left(39-1\right)}{10101.\left(50-7\right)}=\frac{38}{43}\)

\(\frac{-5^3.2.2^6}{3^3.5.2^{14}.5}=\frac{-5^3.2^7}{3^3.5^2.2^{14}}=\frac{-5}{3^3.2^7}\)