Question

đề bài:tính giá trị của biểu thức
a| (3 - 0,6) - (7 + bamộtphầnbốn - 8/5) - (9 - haimộtphầnbốn)
b| (-5/8 + 7/6 - 0/8) - (5/6 - 7/8 - 1,4) + (3/4 + 5/3 + 12/5)

Answer 1

a, ( 3 - 0,6) - ( 7 + 3\(\dfrac{1}{4}\) - \(\dfrac{8}{5}\)) - ( 9 - 2\(\dfrac{1}{4}\))

 = 2,4 - (7 + 3,25 - 1,6) - (9 - 2,25)

= 2,4 - 7 - 3,25 + 1,6 - 9 + 2,25

= (2,4 + 1,6) - (7+ 9) - ( 3,25 - 2,25)

= 4 - 16 - 1

= - 12 - 1

= -13

b, ( - \(\dfrac{5}{8}\) + \(\dfrac{7}{6}\) - \(\dfrac{0}{8}\)) - (\(\dfrac{5}{6}\) - \(\dfrac{7}{8}\) - 1,4) + ( \(\dfrac{3}{4}\) + \(\dfrac{5}{3}\) + \(\dfrac{12}{5}\))

 = - \(\dfrac{5}{8}\) + \(\dfrac{7}{6}\) - \(\dfrac{5}{6}\) + \(\dfrac{7}{8}\) + \(\dfrac{7}{5}\) + \(\dfrac{3}{4}\) +  \(\dfrac{5}{3}\) + \(\dfrac{12}{5}\)

= (- \(\dfrac{5}{8}\) + \(\dfrac{7}{8}\)) + (\(\dfrac{7}{6}\) - \(\dfrac{5}{6}\)) + ( \(\dfrac{7}{5}\) + \(\dfrac{12}{5}\)) + \(\dfrac{3}{4}\) + \(\dfrac{5}{3}\)

= \(\dfrac{1}{4}\) + \(\dfrac{1}{3}\) + \(\dfrac{19}{5}\) + \(\dfrac{3}{4}\) + \(\dfrac{5}{3}\)

= (\(\dfrac{1}{4}\) + \(\dfrac{3}{4}\)) + ( \(\dfrac{1}{3}\) + \(\dfrac{5}{3}\)) + \(\dfrac{19}{5}\)

= 1 + 2 + 3,8

= 6,8