Thực hiện phép tính sau :
-|- 102| + [( -3²). ( - 2) - ( -8)] : 13
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13 - 12 + 11 - 10 - 9 + 8 - 7 - 6 + 5 - 4 + 3 + 2 - 1
= ( 13 - 12 + 11 - 10 + 8 ) - ( 9 + 1 ) - ( 6 + 4) + ( 3 + 2 + 5 ) - 7
= 10 - 10 - 10 + 10 - 7
= ( 10 - 10 ) - ( 10 - 10 ) - 7
= 0 - 0 - 7
= - 7
a) 2/9 - (1/20 + 2/9)
= 2/9 - 1/20 - 2/9
= (2/9 - 2/9) - 1/20
= 0 - 1/20
= -1/20
b) -3/14 + 2/13 + (-25/14) + (-15/13)
= (-3/14 - 25/14) + (2/13 - 15/13)
= -2 - 1
= -3
c) -3/11 + 11/8 - 3/8 + (-8/11)
= (-3/11 - 8/11) + (11/8 - 3/8)
= -1 + 1
= 0
d) 3/8 + (-1/4) - (7/12 - 1/6)
= 1/8 - 5/12
= -7/24
e) (1/3 + 12/67 + 13/41) - (79/67 - 28/41)
= 1/3 + 12/67 + 13/41 - 79/67 + 28/41
= 1/3 + (12/67 - 79/67) + (13/41 + 28/41)
= 1/3 - 1 + 1
= 1/3
13 - 12 + 11 + 10 - 9 + 8 - 7 - 6 + 5 - 4 + 3 + 2 - 1
= 1 + 11 - 1 + 1 + 11 - 7 + 1
= 12 - 1 + 1 + 11 - 7 + 1
= 11 + 1 + 11 - 7 + 1
= 12 + 11 - 7 + 1
= 23 - 7 + 1
= 16 + 1
=17
\(a,\dfrac{2}{5}-\dfrac{3}{8}+\dfrac{7}{6}=\dfrac{16}{40}-\dfrac{15}{40}+\dfrac{7}{6}=\dfrac{1}{40}+\dfrac{7}{6}=\dfrac{3}{120}+\dfrac{140}{120}=\dfrac{143}{120}\)
\(b,\dfrac{2}{3}+\left[\dfrac{5}{7}+\left(-\dfrac{2}{3}\right)\right]=\dfrac{2}{3}+\dfrac{5}{7}+\left(-\dfrac{2}{3}\right)=\left[\dfrac{2}{3}+\left(-\dfrac{2}{3}\right)\right]+\dfrac{5}{7}=0+\dfrac{5}{7}=\dfrac{5}{7}\)
\(c,\dfrac{5}{13}+\left(-\dfrac{5}{7}\right)+\left(-\dfrac{20}{41}\right)+\dfrac{8}{13}+\left(-\dfrac{21}{41}\right)\)
\(=\left(\dfrac{5}{13}+\dfrac{8}{13}\right)-\dfrac{5}{7}-\dfrac{20}{41}-\dfrac{21}{41}=-\dfrac{5}{7}\)
a: =48/120-45/120+140/120
=143/120
b: =2/3-2/3+5/7=5/7
c: =5/13+8/13-5/7-20/41-21/41
=-5/7
Ta có: \(\frac{1}{7}.\frac{-3}{8}+\frac{1}{7}.\frac{-13}{8}\)
\(=\frac{1}{7}.\left(\frac{-3}{8}+\frac{-13}{8}\right)\)
\(=\frac{1}{7}.\left(-2\right)\)
\(=-\frac{2}{7}\)
a)7/8*(-5/14)-13/6
=(-5/16)-13/6
=-119/48
b)(-2/3)^2-13/6
=4/9-13/6
=(-31/18)
c)2/3+3/4:(-5/8)
=2/3+(-6/5)
=(-8/15)