\(\dfrac{3}{5}\div(-\dfrac{1}{15}-\dfrac{1}{6})+\dfrac{3}{5}\div(-\dfrac{1}{3}-1\dfrac{1}{15})\)
K
Khách
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Những câu hỏi liên quan
1 tháng 3 2022
a: =-8/28-7/28=-15/28
b: \(=\dfrac{-4}{18}+\dfrac{3}{7}\cdot\dfrac{14}{15}=\dfrac{-2}{9}+\dfrac{14}{15}=\dfrac{-10+42}{45}=\dfrac{32}{45}\)
c: \(=\dfrac{-3\cdot5+7\cdot2}{20}\cdot\dfrac{-5}{1}-\dfrac{2}{9}\)
\(=\dfrac{-7}{4}-\dfrac{2}{9}=\dfrac{-63}{36}-\dfrac{8}{36}=-\dfrac{71}{36}\)
BS
0,2 \(\times\) \(\dfrac{15}{36}\) - (\(\dfrac{2}{5}\) + \(\dfrac{2}{3}\)) \(\div\) 1\(\dfrac{1}{5}\)
2
PT
2 tháng 5 2017
Tìm x:
a) \(\left(-1\dfrac{1}{5}+x\right):\left(-3\dfrac{3}{5}\right)=-\dfrac{7}{4}+\dfrac{1}{4}:\dfrac{1}{8}\)
\(\left(-1\dfrac{1}{5}+x\right):\left(-3\dfrac{3}{5}\right)=\dfrac{1}{4}\)
\(-1\dfrac{1}{5}+x=\dfrac{1}{4}.\left(-3\dfrac{3}{5}\right)\)
\(-1\dfrac{1}{5}+x=\dfrac{-9}{10}\)
\(\Rightarrow x=\dfrac{3}{10}\)
b) \(\dfrac{5}{7}+\dfrac{2}{3}x=\dfrac{3}{10}\)
\(\dfrac{2}{3}x=\dfrac{3}{10}-\dfrac{5}{7}\)
\(\dfrac{2}{3}x=\dfrac{-29}{70}\)
\(\Rightarrow x=\dfrac{-87}{140}\)
c) \(\dfrac{-22}{15}x+\dfrac{1}{3}=\left|\dfrac{-2}{3}+\dfrac{1}{5}\right|\)
\(-\dfrac{22}{15}x+\dfrac{1}{3}=\dfrac{7}{15}\)
\(\dfrac{-22}{15}x=\dfrac{4}{15}-\dfrac{1}{3}\)
\(\dfrac{-22}{15}x=\dfrac{2}{15}\)
\(\Rightarrow x=\dfrac{-1}{11}\)
24 tháng 7 2017
\(\left[\dfrac{6}{5}-\left(\dfrac{3}{7}-2\dfrac{1}{7}\right):\dfrac{4}{7}\right]\left(-\dfrac{3}{5}\right)+\dfrac{2}{3}:\left(-\dfrac{5}{6}\right)\\ =\left[\dfrac{6}{5}-\left(\dfrac{3}{7}-\dfrac{15}{7}\right)\cdot\dfrac{7}{4}\right]\left(-\dfrac{3}{5}\right)+\dfrac{2}{3}\cdot\left(-\dfrac{6}{5}\right)\\ =\left[\dfrac{6}{5}+3\right]\left(-\dfrac{3}{5}\right)-\dfrac{4}{5}\\ =\dfrac{21}{5}\cdot\left(-\dfrac{7}{5}\right)\\ =-\dfrac{147}{25}\)
24 tháng 7 2017
câu a thì 15 nhân voi 3/5 hay là \(15\dfrac{3}{5}\) là một hỗn số
28 tháng 6 2021
`a)((sqrt(14)-sqrt7)/(1-sqrt2)+(sqrt{15}-sqrt5)/(1-sqrt3)):1/(sqrt7-sqrt5)`
`=((sqrt7(sqrt2-1))/(1-sqrt2)+(sqrt5(sqrt3-1))/(1-sqrt3)).(sqrt7-sqrt5)`
`=(-sqrt7-sqrt5)*(sqrt7-sqrt5)`
`=-(sqrt7+sqrt5)(sqrt7+sqrt5)`
`=-(7-5)=-2`
`b)sqrt2+1/sqrt{5+2sqrt6}+2/sqrt{8+2sqrt{15}}`
`=sqrt2+1/sqrt{3+2sqrt{3}.sqrt2+2}+2/sqrt{5+2sqrt{5}.sqrt3+3}`
`=sqrt2+1/sqrt{(sqrt3+sqrt2)^2}+2/sqrt{(sqrt5+sqrt3)^2}`
`=sqrt2+1/(sqrt3+sqrt2)+2/(sqrt5+sqrt3)`
`=sqrt2+((sqrt3+sqrt2)(sqrt3-sqrt2))/(sqrt3+sqrt2)+((sqrt5+sqrt3)(sqrt5-sqrt3))/(sqrt5+sqrt3)`
`=sqrt2+sqrt3-sqrt2+sqrt5-sqrt3=sqrt5`
28 tháng 6 2021
a) Ta có: \(\left(\dfrac{\sqrt{14}-\sqrt{7}}{1-\sqrt{2}}+\dfrac{\sqrt{15}-\sqrt{5}}{1-\sqrt{3}}\right):\dfrac{1}{\sqrt{7}-\sqrt{5}}\)
\(=\left(-\dfrac{\sqrt{7}\left(1-\sqrt{2}\right)}{1-\sqrt{2}}-\dfrac{\sqrt{5}\left(1-\sqrt{3}\right)}{1-\sqrt{3}}\right):\dfrac{1}{\sqrt{7}-\sqrt{5}}\)
\(=-2\)
b) Ta có: \(\sqrt{2}+\dfrac{1}{\sqrt{5+2\sqrt{6}}}+\dfrac{2}{\sqrt{8+2\sqrt{15}}}\)
\(=\sqrt{2}+\dfrac{1}{\sqrt{3}+\sqrt{2}}+\dfrac{2}{\sqrt{5}+\sqrt{3}}\)
\(=\sqrt{2}+\sqrt{3}-\sqrt{2}+\sqrt{5}-\sqrt{3}\)
\(=\sqrt{5}\)
31 tháng 12 2022
a: =>x*2/15=2/7
=>x=2/7:2/15=2/7*15/2=15/7
b: x=3:7/5=15/7
c: x=-1/2:4/9=-1/2*9/4=-9/8
d: x=-8/3:3/8=-64/9
g: =>4/11x=2/5+1/3=6/15+5/15=11/15
=>x=11/15:4/11=121/60
l: =>1/4:x=1-3/2=-1/2
=>x=-1/4:1/2=-1/4*2=-1/2
k: =>x:7=-1/3+5/2=-2/6+15/6=13/6
=>x=91/6
16 tháng 10 2018
b) \(\dfrac{7}{15}-\dfrac{9}{19}\)\(-\dfrac{-8}{15}-\dfrac{10}{19}\)
=\(\left(\dfrac{7}{15}-\dfrac{8}{15}\right)\) \(-\left(\dfrac{9}{19}-\dfrac{10}{19}\right)\)
= \(-\dfrac{1}{15}\) - \(\left(-\dfrac{1}{19}\right)\)
\(=-\dfrac{1}{15}\) + \(\dfrac{1}{19}\)
= \(-\dfrac{4}{285}\)
16 tháng 10 2018
c) \(1\dfrac{1}{3}\) \(\div\) \(\dfrac{4}{5}\) + 2\(\dfrac{2}{3}\) \(\div\)\(\dfrac{4}{5}\)
= \(\left(1\dfrac{1}{3}+2\dfrac{2}{3}\right)\) \(\div\dfrac{4}{5}\)
= \(\left[\left(1+2\right)+\left(\dfrac{1}{3}+\dfrac{2}{3}\right)\right]\) \(\div\dfrac{4}{5}\)
= ( 3 + 1 ) \(\div\dfrac{4}{5}\)
= 4 \(\div\dfrac{4}{5}\)
= \(\dfrac{4.5}{4}\)
= 5
VN
Võ Ngọc Phương
CTVHS
VIP
24 tháng 7 2023
\(\dfrac{15}{16}:\dfrac{5}{8}\times\dfrac{3}{4}\)
\(=\dfrac{15}{16}\times\dfrac{8}{5}\times\dfrac{3}{4}\)
\(=\dfrac{3}{2}\times\dfrac{3}{4}\)
\(=\dfrac{9}{8}\)
_________________
\(\dfrac{21}{4}\times\dfrac{16}{14}\times\dfrac{1}{2}\times\dfrac{8}{3}\)
\(=6\times\dfrac{4}{3}\)
\(=8\)
6 tháng 5 2017
e) \(\dfrac{-3}{5}.\dfrac{2}{7}+\dfrac{-3}{5}.\dfrac{5}{7}+2\dfrac{3}{5}\)
= \(\dfrac{-3}{5}.\left(\dfrac{2}{7}+\dfrac{5}{7}\right)+\dfrac{13}{5}\)
= \(\dfrac{-3}{5}.1+\dfrac{13}{5}\)
= \(\dfrac{-3}{5}+\dfrac{13}{5}\)
= 2
`3/5:(-1/15-1/6)+3/5:(-1/3-1 1/15)`
`=3/5:[-7]/30+3/5:[-7]/5`
`=3/5 . [-30]/7+3/5 . [-5]/7`
`=3/5 .([-30]/7+[-5]/7)`
`=3/5 . [-5]=-3`
\(\dfrac{3}{5}:\left(-\dfrac{1}{15}-\dfrac{1}{6}\right)+\dfrac{3}{5}:\left(-\dfrac{1}{3}-1\dfrac{1}{15}\right)\)
\(=\dfrac{3}{5}:\left(-\dfrac{6}{90}-\dfrac{15}{90}\right)+\dfrac{3}{5}:\left(-\dfrac{1}{3}-\dfrac{16}{15}\right)\)
\(=\dfrac{3}{5}:\dfrac{-7}{30}+\dfrac{3}{5}:\left(-\dfrac{5}{15}-\dfrac{16}{15}\right)\)
\(=\dfrac{3}{5}:\dfrac{-7}{30}+\dfrac{3}{5}:\dfrac{-7}{5}\)
\(=\dfrac{3}{5}\times\dfrac{-30}{7}+\dfrac{3}{5}\times\dfrac{-5}{7}\)
\(=\dfrac{3}{5}\times\left(\dfrac{-30}{7}+\dfrac{-5}{7}\right)\)
\(=\dfrac{3}{5}\times\left(-5\right)\)
\(=-3\)