Question

[do khanh san]

Tính nhanh giá trị mỗi biểu thức sau :

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

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

Answer 1

[Nguyễn Thị Thu Hà]

Tính bằng cách thuận tiên nhât 28/35×15/12×26/19

Answer 2

[Nguyễn Thị Thương Hoài]

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 = - \(\dfrac{5}{27}\)