Tính :
\(a.\frac{-9}{34}.\frac{17}{4}\)
\(b,\frac{-20}{41}.\frac{-4}{5}\)
K
Khách
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21 tháng 6 2015
a,\(=\frac{-5}{9}+\frac{8}{15}+\frac{-2}{11}+\frac{-4}{9}+\frac{7}{15}\)
\(\left(\frac{-5}{9}+\frac{-4}{9}\right)+\left(\frac{8}{15}+\frac{7}{15}\right)+\frac{-2}{11}\)
=-1+1+-2/11
=0+-2/11
=-2/11
b,\(=\left(\frac{5}{13}+\frac{8}{13}\right)+\left(\frac{-20}{41}+\frac{-21}{40}\right)+\frac{-5}{17}\)
=1+-1+-5/17
=0+-5/17
=-5/17
c,\(=\left(\frac{1}{5}+\frac{4}{5}\right)+\left(\frac{-2}{9}+-\frac{7}{9}\right)+\frac{16}{17}\)
=1+-1+16/17
=0+16/17
=16/17
d,\(=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+...+\frac{1}{99}-\frac{1}{101}\)
\(=\frac{1}{3}-\frac{1}{101}=\frac{98}{303}\)
21 tháng 6 2015
a.\(\frac{-5}{9}\)+\(\frac{8}{15}\)+\(\frac{-2}{11}\)+\(\frac{4}{-9}\)+\(\frac{7}{15}\)
=\(\frac{-5}{9}\)+\(\frac{4}{-9}\)+\(\frac{8}{15}\)+\(\frac{7}{15}\)+\(\frac{-2}{11}\)
=(\(\frac{-5}{9}\)+\(\frac{-4}{9}\))+(\(\frac{8}{15}\)+\(\frac{7}{15}\))+\(\frac{-2}{11}\)
=(-1)+1+\(\frac{-2}{11}\)
=0+\(\frac{-2}{11}\)
=\(\frac{-2}{11}\).
26 tháng 9 2020
Bài 3:
a) Ta có: \(1.25\cdot\left(-3\frac{3}{8}\right)\)
\(=\frac{5}{4}\cdot\frac{-27}{8}\)
\(=\frac{-135}{32}\)
b) Ta có: \(\frac{-9}{34}\cdot\frac{17}{4}\)
\(=\frac{-9}{4}\cdot\frac{17}{34}\)
\(=-\frac{9}{4}\cdot\frac{1}{2}\)
\(=-\frac{9}{8}\)
c) Ta có: \(-\frac{20}{41}\cdot\frac{-4}{5}\)
\(=\frac{20}{41}\cdot\frac{4}{5}\)
\(=\frac{16}{41}\)
d) Ta có: \(\frac{-6}{7}\cdot\frac{21}{2}\)
\(=-\frac{6}{2}\cdot\frac{21}{7}\)
\(=-3\cdot3=-9\)
Bài 4:
a) Ta có: \(-\frac{5}{2}\cdot\frac{3}{4}\)
\(=-\frac{5\cdot3}{2\cdot4}=\frac{-15}{8}\)
b) Ta có: \(4\frac{1}{5}:\left(-2\frac{4}{5}\right)\)
\(=-\frac{21}{5}:\frac{14}{5}\)
\(=-\frac{21}{5}\cdot\frac{5}{14}\)
\(=-\frac{21}{14}=-\frac{3}{2}\)
c) Ta có: \(1.8:\left(-\frac{3}{4}\right)\)
\(=\frac{9}{5}:\frac{-3}{4}\)
\(=\frac{9}{5}\cdot\frac{4}{-3}\)
\(=-\frac{12}{5}\)
d) Ta có: \(\frac{17}{15}:\frac{4}{3}\)
\(=\frac{17}{15}\cdot\frac{3}{4}\)
\(=\frac{17}{20}\)
26 tháng 7 2016
p) \(\frac{-5}{9}+\frac{8}{15}+\frac{-2}{11}+\frac{4}{-9}+\frac{7}{15}\)
\(=\left(\frac{-5}{9}+\frac{-4}{9}\right)+\left(\frac{8}{15}+\frac{7}{15}\right)+\frac{-2}{11}\)
\(=-1+1+\frac{-2}{11}\)
\(=-\frac{2}{11}\)
q) \(\frac{5}{13}+\frac{-5}{17}+\frac{-20}{41}+\frac{8}{13}+\frac{-21}{41}\)
\(=\left(\frac{5}{13}+\frac{8}{13}\right)+\left(\frac{-20}{41}+\frac{-21}{41}\right)+\frac{-5}{17}\)
\(=1+\left(-1\right)+\frac{-5}{17}=\frac{-5}{17}\)
r) \(\frac{1}{5}+\frac{-2}{9}+\frac{-7}{9}+\frac{4}{5}+\frac{16}{17}\)
\(=\left(\frac{1}{5}+\frac{4}{5}\right)+\left(\frac{-2}{9}+\frac{-7}{9}\right)+\frac{16}{17}\)
\(=1+\left(-1\right)+\frac{16}{17}=\frac{16}{17}\)
N
10 tháng 9 2019
a, Vì 4 < 16 < 64 < 256 (Khi lập TLT luôn lấy số lớn nhất nhân số bé nhất trước rồi mới đến 2 số còn lại)
Ta có: 256.4 = 1024
64.16 = 1024
=> 256.4 = 64.16
\(\Rightarrow\frac{256}{64}=\frac{16}{4};\)\(\frac{256}{16}=\frac{64}{4};\)\(\frac{4}{64}=\frac{16}{256};\)\(\frac{4}{16}=\frac{64}{256}\)
12 tháng 12 2021
\(\text{a)}A=\frac{9}{11}+\frac{5}{7}-\frac{20}{11}+\frac{8}{13}+\frac{2}{7}\)
\(A=\frac{9}{11}+\frac{5}{7}+\frac{-20}{11}+\frac{8}{13}+\frac{2}{7}\)
\(A=\left(\frac{9}{11}+\frac{-20}{11}\right)+\left(\frac{5}{7}+\frac{2}{7}\right)+\frac{8}{13}\)
\(A=\frac{-11}{11}+\frac{7}{7}+\frac{8}{13}\)
\(A=\left[\left(-1\right)+1\right]+\frac{8}{13}\)
\(A=0+\frac{8}{13}=\frac{8}{13}\)
\(\text{b)}B=\frac{8}{13}+\frac{9}{-17}+\frac{-34}{13}+\frac{-8}{17}\)
\(B=\left(\frac{8}{13}+\frac{-34}{13}\right)+\left(\frac{-9}{17}+\frac{-8}{17}\right)\)
\(B=\frac{-26}{13}+\left(-1\right)\)
\(B=\left(-2\right)+\left(-1\right)=-3\)
\(\text{Hok tốt!}\)
\(\text{@Kaito Kid}\)
5 tháng 9 2019
A = 5/7.(1+9/13) − 5/7.9/13
A= 5/7.(1+9/13 - 9/13)
A = 5/7.1
A = 5/7
B = 11/24 − 5/41 + 13/24 + 0.5 − 36/41
B = (11/24 + 13/24) - (5/41 + 36/41) + 0.5
B = 1 - 1 + 0.5
B = 0.5
C = −4/13.5/17 + (−12/13).4/17 + 4/13
C = 4/13.(-5/17) + (−12/13).4/17 + 4/13
C = 4/13.(-5/17 + 1) + (−12/13).4/17
C = 4/13.(−12/17) + (−12/13).4/17
C = (4.-12)/(13.17) + (−12/13).4/17
C = 4/17.(−12/13) + (−12/13).4/17
C = 4/17.(−12/13).2
C = 96/221
D = (4/3 − 3/2)2 − 2.∣−1/9∣ + (−5/18)
D = (4/3 − 3/2)2 − 2.1/9+ (−5/18)
D = -1/62 - 2/9+ (−5/18)
D = -1/12 - ( 2/9+ (−5/18) )
D = -1/12 - ( 4/18+ (−5/18) )
D = -1/12 - (-1/18)
D = -1/12 + 1/18
D = -3/36 + 2/36
D = -1/36
E = (−3/4 + 2/3):5/11 + (−1/4 + 1/3):5/11
E = (−3/4 + 2/3 + (−1/4) + 1/3):5/11
E = ((−3/4 + (−1/4)) + (2/3 + + 1/3)):5/11
E = ( - 1 + 1):5/11
E = 0:5/11
E = 0
16 tháng 5 2020
tìm n 
giúp mik với sắp thi r
a)\(\frac{-9}{34}.\frac{17}{4}=\frac{-3^2.17}{17.2^3}=-1\)
b)\(\frac{-20}{41}.\frac{-4}{5}=\frac{5.16}{41.5}=\frac{16}{41}\)
Hok tốt
\(a.\frac{-9}{34}.\frac{17}{4}=\frac{-9.17}{34.4}=\frac{-9.1}{2.4}=-\frac{9}{8}\)
\(b.-\frac{20}{41}.\frac{-4}{5}=\frac{-20.\left(-4\right)}{41.5}=\frac{-4.\left(-4\right)}{41.1}=\frac{16}{41}\)
hok tốt
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