Thôi, để mk giải chi tiết cho, không lại bảo mk lười:

A=\(\dfrac{18}{26}+\dfrac{-5}{27}+\dfrac{-22}{86}+\dfrac{12}{39}+\dfrac{-32}{43}\)

A=\(\dfrac{9}{13}+\dfrac{-5}{27}+\dfrac{-11}{43}+\dfrac{4}{13}+\dfrac{-32}{43}\)

A=\(\left(\dfrac{9}{13}+\dfrac{4}{13}\right)+\left(\dfrac{-11}{43}+\dfrac{-32}{43}\right)+\dfrac{-5}{27}\)

A= 1+(-1)+\(\dfrac{-5}{27}\)

A=0+\(\dfrac{-5}{27}\)

A=\(\dfrac{-5}{27}\)

B=\(\dfrac{-10}{12}+\dfrac{8}{15}+\dfrac{-19}{56}+\dfrac{-3}{18}+\dfrac{28}{60}\)

B=\(\dfrac{-5}{6}+\dfrac{8}{15}+\dfrac{-19}{56}+\dfrac{-1}{6}+\dfrac{7}{15}\)

B=\(\left(\dfrac{-5}{6}+\dfrac{-1}{6}\right)+\left(\dfrac{8}{15}+\dfrac{7}{15}\right)+\dfrac{-19}{56}\)

B= -1+1+\(\dfrac{-19}{56}\)

B=0+\(\dfrac{-19}{56}\)

B=\(\dfrac{-19}{56}\)

Ôi mỏi quá! Chúc bạn học tốt !

Help!

Cái nào rút gọn được thì rút gọn rồi quy đồng lên (hoặc sử dụng vài tính chất để tính nhanh nếu có thể)

A = \(\dfrac{18}{26}\) + (-\(\dfrac{5}{27}\)) + (-\(\dfrac{22}{86}\)) + \(\dfrac{12}{39}\) - \(\dfrac{32}{43}\)

A = \(\dfrac{9}{13}\) - \(\dfrac{5}{27}\) -  \(\dfrac{11}{43}\) + \(\dfrac{4}{13}\) - \(\dfrac{32}{43}\)

A = (\(\dfrac{9}{13}\) + \(\dfrac{4}{13}\)) - (\(\dfrac{11}{43}\) + \(\dfrac{32}{43}\)) - \(\dfrac{5}{27}\)

A = \(\dfrac{13}{13}\) - \(\dfrac{43}{43}\) - \(\dfrac{5}{27}\)

A = 1 - 1 - \(\dfrac{5}{27}\)

A = 0 - \(\dfrac{5}{27}\)

A = - \(\dfrac{5}{27}\)

B = -\(\dfrac{10}{12}\) + \(\dfrac{8}{15}\) - \(\dfrac{19}{56}\) + \(\dfrac{3}{-18}\) + \(\dfrac{28}{60}\)

B = - \(\dfrac{5}{6}\) + \(\dfrac{8}{15}\) - \(\dfrac{19}{56}\) - \(\dfrac{1}{6}\) + \(\dfrac{7}{15}\)

B = -(\(\dfrac{5}{6}\) + \(\dfrac{1}{6}\)) - \(\dfrac{19}{56}\) + (\(\dfrac{8}{15}\) + \(\dfrac{7}{15}\))

B = -1  - \(\dfrac{19}{56}\) + 1

B = - \(\dfrac{19}{56}\) 

hãy quy đồng các phân số sau

A = 18/26 + -5/27 + -22/86 + 12/39 + -32/43 

A = 9/13 + -5/27 + -11/43 + 4/13 + -32/43

A = -5/27 + ( 9/13 + 4/13 ) + ( -11/43 + -32/43 )

A = -5/27 + 1 + ( -1)

A = -5/27 + 0 

A = 0

B = -10/12 + 8/15 + -19/56 + 3/-18 + 28/60

B = -5/6 + 8/15 + -19/56 + -1/6 + 7/15

B = -19/56 + ( -5/6 + -1/6 ) + ( 8/15 + 7/15 ) 

B = -19/56 + ( -1 ) + 1

B = -19/56 + 0

B = 0

Thông cảm ...Vì không biết sử dụng phân số nên đành viết bằng dấu gạch chéo

a) \(\dfrac{3}{35}+\dfrac{7}{20}+\dfrac{32}{35}+\dfrac{13}{20}\)

Áp dụng tính chất giao hoán, kết hợp của phép cộng, ta được:

\(\left(\dfrac{3}{35}+\dfrac{32}{35}\right)+\left(\dfrac{7}{20}+\dfrac{13}{20}\right)\)

\(=1+1\)

\(=2\)

b) \(\dfrac{18\cdot15\cdot56}{42\cdot27\cdot25}=\dfrac{2\cdot3\cdot3\cdot5\cdot3\cdot4\cdot2\cdot7}{2\cdot3\cdot2\cdot2\cdot3\cdot9\cdot5\cdot5}\)

\(=\dfrac{2\cdot2\cdot3\cdot3\cdot3\cdot4\cdot5\cdot7}{2\cdot2\cdot2\cdot3\cdot3\cdot5\cdot5\cdot9}=\dfrac{3\cdot2\cdot2\cdot7}{2\cdot5\cdot9}=\dfrac{42}{45}\)

1; - (-66) + 34 + (-73) - 27 + 99 

=  66 + 34 - 73 - 27 + 99

=  (66 + 34) - (73 + 27) + 99

=  100 - 100 + 99

=  0 + 99

=    99

2; 54 - (45 - 30 + 54) - 30 + 5

= 54 - 45 + 30 - 54 - 30 + 5

= (54 - 54) + (30 - 30) - (45 - 5)

= 0 + 0 - 40

= - 40 

3; 42 - 56 + 33 - (33 + 56 + 42)

= 42 - 56 + 33 - 33 - 56 - 42

= (42 - 42) - (33 - 33) - (56 + 56)

= 0 - 0 - 112

= - 112