B = 3003 x 30013001 - 3001 x 30033003

B = 3003 x 3001 x 10001 - 3001 x 3003 x 10001

=> B = \(0\)

B=3003x30013001-3001x30033003 

=> B = 0 

B = 3003 x 30013001 - 3001 x 30033003

   = 3003 x 3001 x 10001 - 3001 x 3003 x 10001 = 0

-180

-180

tính đoàng hoàng đi

25,3

Sửa đề: 3/91*96

\(B=\dfrac{3}{1\cdot6}+\dfrac{3}{6\cdot11}+...+\dfrac{3}{91\cdot96}\)

=3/5(5/1*6+5/6*11+...+5/91*96)

=3/5(1-1/6+1/6-1/11+...+1/91-1/96)

=3/5*95/96=57/96=19/32

Bài 1: 

b: \(=\left(\dfrac{27}{23}-\dfrac{4}{23}\right)+\left(\dfrac{5}{21}+\dfrac{16}{21}\right)+\dfrac{1}{2}=\dfrac{1}{2}\)

c: \(=\dfrac{1}{9}\left(\dfrac{2}{9}+\dfrac{7}{9}\right)-\dfrac{8}{9}=\dfrac{1}{9}-\dfrac{8}{9}=-\dfrac{7}{9}\)

Bài 2: 

b: \(\Leftrightarrow x+\dfrac{3}{10}=\dfrac{17}{30}\)

hay x=4/15

\(\dfrac{1}{x^2-x}+\dfrac{x-3}{x^2-1}\left(x\ne\pm1;x\ne0\right)\)

\(=\dfrac{1}{x\left(x-1\right)}+\dfrac{x-3}{\left(x-1\right)\left(x+1\right)}\)

\(=\dfrac{x+1}{x\left(x-1\right)\left(x+1\right)}+\dfrac{x\left(x-3\right)}{x\left(x-1\right)\left(x+1\right)}\)

\(=\dfrac{x+1+x^2-3x}{x\left(x-1\right)\left(x+1\right)}\)

\(=\dfrac{x^2-2x+1}{\left(x-1\right)\left[x\left(x+1\right)\right]}\)

\(=\dfrac{\left(x-1\right)^2}{\left(x-1\right)\left(x^2+x\right)}\)

\(=\dfrac{x-1}{x^2+x}\)