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a) 1/2 + 3/4 - (3/4 - 4 - 5)
= 1/2 + 3/4 - 3/4 + 4 + 5
= (3/4 - 3/4) + (4 + 5) + 1/2
= 0 + 9 + 1/2
= 19/2
b) [9/16 + 8/(-27)] - (19/27- 7/16 - 2)
= 9/16 - 8/27 - 19/27 + 7/16 + 2
= (9/16 + 7/16) + (-8/27 - 19/27) + 2
= 1 - 1 + 2
= 2
c) -5/8 . [4/9 + 7/(-12)]
= -5/8 . (-5/36)
= 25/288
d) 7/10 . (-3/5) + 7/10 . (-2/5) - (-3/10)
= 7/10 . (-3/5 - 2/5) + 3/10
= 7/10 . (-1) + 3/10
= -2/5
e) -3/7 . 5/9 + 4/9 . (-3/7) + 2 3/7
= -3/7 . (5/9 + 4/9) + 17/7
= -3/7 . 1 + 17/7
= 2
f) 8 2/7 - (3 4/9 + 4 2/7)
= 8 + 2/7 - 3 - 4/9 - 4 - 2/7
= (8 - 3 - 4) + (2/7 - 2/7) - 4/9
= 1 - 4/9
= 5/9
h) 3.(-1/2)² - (4/5 + 8/15) : 5/6
= 3.1/4 - 4/3 : 5/6
= 3/4 - 8/5
= -17/20
a; - \(\dfrac{10}{13}\) + \(\dfrac{5}{17}\) - \(\dfrac{3}{13}\) + \(\dfrac{12}{17}\) - \(\dfrac{11}{20}\)
= - (\(\dfrac{10}{13}\) + \(\dfrac{3}{13}\)) + (\(\dfrac{5}{17}\) + \(\dfrac{12}{17}\)) - \(\dfrac{11}{20}\)
= - 1 + 1 - \(\dfrac{11}{20}\)
= 0 - \(\dfrac{11}{20}\)
= - \(\dfrac{11}{20}\)
b; \(\dfrac{3}{4}\) + \(\dfrac{-5}{6}\) - \(\dfrac{11}{-12}\)
= \(\dfrac{9}{12}\) - \(\dfrac{10}{12}\) + \(\dfrac{11}{12}\)
= \(\dfrac{10}{12}\)
= \(\dfrac{5}{6}\)
c; [13.\(\dfrac{4}{9}\) + 2.\(\dfrac{1}{9}\)] - 3.\(\dfrac{4}{9}\)
= [\(\dfrac{52}{9}\) + \(\dfrac{2}{9}\)] - \(\dfrac{4}{3}\)
= \(\dfrac{54}{9}\) - \(\dfrac{4}{3}\)
= \(\dfrac{14}{3}\)
Câu 9
a) 2/15 + (-3/5)
= 2/15 - 3/5
= 2/15 - 9/15
= -7/15
b) -5/7 + 3/7 . (-2/9)
= -5/7 - 2/21
= -15/21 - 2/21
= -17/21
c) 5/16 - (7/15 - 3/16) + 17/30
= 5/16 - 7/15 + 3/16 + 17/30
= (5/16 + 3/16) + (17/30 - 14/30)
= 1/2 + 1/10
= 5/10 + 1/10
= 6/10
= 3/5
\(a,\dfrac{2}{15}+\left(-\dfrac{3}{5}\right)\\ =\dfrac{2}{15}-\dfrac{3}{5}\\ =\dfrac{2}{15}-\dfrac{9}{15}\\ =-\dfrac{7}{15}\\ b,-\dfrac{5}{7}+\dfrac{3}{7}\times\left(-\dfrac{2}{9}\right)\\ =-\dfrac{5}{7}-\dfrac{2}{21}\\ =-\dfrac{15}{21}-\dfrac{2}{21}\\ =-\dfrac{17}{21}\\ c,\dfrac{5}{16}-\left(\dfrac{7}{15}-\dfrac{3}{16}\right)+\dfrac{17}{30}\\ =\dfrac{5}{16}-\dfrac{7}{15}+\dfrac{3}{16}+\dfrac{17}{30}\\ =\left(\dfrac{5}{16}+\dfrac{3}{16}\right)-\left(\dfrac{17}{15}+\dfrac{17}{30}\right)\\ =\dfrac{1}{2}-\dfrac{17}{10}\\ =\dfrac{5}{10}-\dfrac{17}{10}\\ =-\dfrac{6}{5}.\)
Bài 1 :
a, 25 + (-42) = - ( 42 - 25 ) = - 17
b, (-17) + 5 + 8 + 17 + (-3 )
= [ (-17) + 17 ] + [ ( 5 + 8 ) + (-3) ]
= 0 + 10
= 10
c, 25. 22 - ( 15-18 ) + ( 12 - 19 + 10 )
= 25 . 4 - (-3) + 3
= 100 - [ (-3) + 3 ]
= 100 - 0
= 100
d, 120 - 35 + 29 - 242
= 85 + 29 - 242
= 114 - 242
= -128
a, \(\left(-17\right)+5+8+17+\left(-3\right)\)
\(=\left(-17+17\right)+\left[5+\left(-3\right)\right]+8\)
\(=0+8+8=8+8=16\)
b, \(\left(5^{19}:5^{17}+3\right):7=\left(5^2+3\right):7\)
\(=\left(25+3\right):7=28:7=4\)
c, \(|-8|+\left(-5\right)+9+\left(-7\right)+|-4|\)
\(=8-5+9-7+4=3+2+4=5+4=9\)
ý d mk ko biết nha.
thông cảm cho mk nha.
k mk nha.
#mon
Mn giúp mh với đg cần gấp lắm ln🥺🥺