A=-3/4+(2+-1/4)
B= 6/7.8/13+6/7.9/13-4/13.6/7
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28 tháng 3 2021
\(a,\dfrac{2}{3}-\dfrac{5}{6}+\dfrac{3}{4}\)
\(=(\dfrac{2}{3}+\dfrac{3}{4})-\dfrac{5}{6}\)
\(=\dfrac{7}{12}\)
\(b,\dfrac{6}{7}.\dfrac{8}{13}+\dfrac{6}{13}.\dfrac{9}{7}-\dfrac{-4}{13}.\dfrac{6}{7}\)
\(=\dfrac{6}{7}.(\dfrac{8}{13}-\dfrac{4}{13})+(\dfrac{6}{13}.\dfrac{9}{7})\)
\(=(\dfrac{6}{7}.\dfrac{4}{13})+\dfrac{54}{91}\)
\(=\dfrac{24}{91}+\dfrac{54}{91}\)
\(=\dfrac{78}{91}=\dfrac{6}{7}\)
\(c,19.(-26)\)
\(=-494\)
TA
28 tháng 3 2021
a) `2/3 - 5/6 +3/4`
`=4/6-5/6+3/4`
`=-1/6+3/4`
`=-4/24+18/24`
`=14/24=7/12`
b) `6/7 .8/13 +6/13 .9/7 -4/13 .6/7`
`=6/7 .(8/13-4/13) + 6/13 .9/7`
`=6/7 . 4/13 + 6/13 . 9/7`
`= 6/13 .4/7 +6/13 .9/7`
`=6/13 . (4/7+9/7)`
`=6/13 . 13/7`
`=6/7`
c) `19.(-26)`
`=(1-20).(20+6)`
`=20+6-400-120`
`=-494`
NT
1
A
2
1 tháng 5 2016
- 6/7.8/13+6/13.9/7-3/13.6/7
- (-3,2).15/64+(0,8-2 4/15):3 2/3
- 1,4.15/49-(4/5+2/3):2 1/5
/ là phân số
1 tháng 5 2016
1.=6/7.8/13+6/7.9/13-3/13.6/7=6/7.(8/13+9/13-3/13)=6/7.14/13=12/13
28 tháng 4 2020
Ta có: \(\frac{6}{7}\cdot\frac{8}{13}+\frac{9}{13}\cdot\frac{6}{7}-\frac{3}{13}\cdot\frac{6}{7}\)
\(=\frac{6}{7}\cdot\left(\frac{8}{13}+\frac{9}{13}-\frac{3}{13}\right)\)
\(=\frac{6}{7}\cdot\frac{14}{13}=2\cdot\frac{6}{13}=\frac{12}{13}\)
1 tháng 10 2021
\(a,=\dfrac{3}{2}-\dfrac{5}{6}:\dfrac{1}{4}+\sqrt{\dfrac{1}{4}-\dfrac{1}{2}}=\dfrac{3}{2}-\dfrac{10}{3}+\sqrt{\dfrac{1}{2}}=-\dfrac{11}{6}+\dfrac{\sqrt{2}}{2}=\dfrac{-33+3\sqrt{2}}{6}\)
\(b,=-\dfrac{4}{3}\cdot\dfrac{9}{2}+\dfrac{13}{12}\cdot\left(-\dfrac{8}{13}\right)=6-\dfrac{2}{3}=\dfrac{16}{3}\\ c,=\dfrac{1}{4}-\left(-\dfrac{1}{6}:4-8\cdot\dfrac{1}{16}\right)=\dfrac{1}{4}-\left(-\dfrac{1}{24}-\dfrac{1}{2}\right)\\ =\dfrac{1}{4}-\dfrac{13}{24}=-\dfrac{7}{24}\\ d,=\dfrac{3^{11}\cdot5^{11}\cdot5^7\cdot3^4}{5^{18}\cdot3^{18}}=\dfrac{1}{3^3}=\dfrac{1}{27}\)
N
3
2
20 tháng 4 2022
`6 / 7 . 8 / 13 + 6 / 13 . 9 / 7 - 4 / 13 . 6 / 7`
`= 6 / 7 . 8 / 13 + 6 / 7 . 9 / 13 - 4 / 13 . 6 / 7`
`= 6 / 7 ( 8 / 13 + 9 / 13 - 4 / 13 )`
`= 6 / 7 . 13 / 13`
`= 6 / 7`
VD
20 tháng 4 2022
\(\dfrac{6}{7}.\dfrac{8}{13}+\dfrac{6}{13}.\dfrac{9}{7}-\dfrac{4}{13}.\dfrac{6}{7}\\ =\dfrac{6}{7}.\dfrac{8}{13}+\dfrac{6}{7}.\dfrac{9}{13}-\dfrac{4}{13}.\dfrac{6}{7}\\ =\dfrac{6}{7}\left(\dfrac{8}{13}+\dfrac{9}{13}-\dfrac{4}{13}\right)\\ =\dfrac{6}{7}.\dfrac{13}{13}\\ =\dfrac{6}{7}.1\\ =\dfrac{6}{7}\)
LT
a)-4/11+5/6+7/11-5/6
b)-5/6.7/13+19/13.6/-5+2/5
c)3/7.(-0,5+3/2)-2/7:25%
mọi người giúp e vs ạ
e cần gấp
3
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
19 tháng 2 2024
a; - \(\dfrac{4}{11}\) + \(\dfrac{5}{6}\) + \(\dfrac{7}{11}\) - \(\dfrac{5}{6}\)
= (-\(\dfrac{4}{11}\) + \(\dfrac{7}{11}\)) + (\(\dfrac{5}{6}\) - \(\dfrac{5}{6}\))
= - \(\dfrac{3}{11}\) + 0
= - \(\dfrac{3}{11}\)
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
19 tháng 2 2024
b; -\(\dfrac{5}{6}\).\(\dfrac{7}{13}\) + \(\dfrac{19}{13}\).\(\dfrac{6}{-5}\) + \(\dfrac{2}{5}\)
= - \(\dfrac{35}{78}\) - \(\dfrac{114}{65}\) + \(\dfrac{2}{5}\)
= - \(\dfrac{859}{390}\) + \(\dfrac{2}{5}\)
= - \(\dfrac{703}{390}\)
30 tháng 1 2020
Câu 1 dễ mà :
1.2.3...9 - 1.2.3...8 - 1.2.3...7.82
= 1.2.3...8.9 - 1.2.3...8.1 - 1.2.3...7.8.8
= 1.2.3...8.( 9 - 1 - 8 )
= 1.2.3...8.0
= 0
A=1
B=6/7
\(A=-\dfrac{3}{4}+\left[2+\left(-\dfrac{1}{4}\right)\right]\\ =-\dfrac{3}{4}+2-\dfrac{1}{4}\\ =-\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+2\\ =\left(-1\right)+2=1\\ B=\dfrac{6}{7}\cdot\dfrac{8}{13}+\dfrac{6}{7}\cdot\dfrac{9}{13}-\dfrac{4}{13}\cdot\dfrac{6}{7}\\ =\dfrac{6}{7}\cdot\left(\dfrac{8}{13}+\dfrac{9}{13}-\dfrac{4}{13}\right)\\ =\dfrac{6}{7}\cdot\dfrac{13}{13}=\dfrac{6}{7}\)