\(-\dfrac{\text{11}}{\text{24}}:\dfrac{\text{17}}{\text{23}}-\dfrac{\text{11}}{\text{24}}:\dfrac{\text{17}}{\text{11}}-\dfrac{1}{\text{12}}\)
\(\dfrac{\text{3}}{17}\text{+}\dfrac{\text{\text{-}5}}{\text{1}\text{3}}\text{+}\dfrac{\text{1}\text{8}}{\text{3}\text{5}}\text{+}\dfrac{\text{14}}{\text{17}}\text{+}\dfrac{\text{17}}{\text{\text{-}35}}\text{+}\dfrac{\text{ }\text{-}\text{8}}{\text{\text{1}\text{3}}}\)=?
\(\dfrac{\text{\text{ }\text{-}\text{3}}}{\text{8}}\text{+}\dfrac{\text{1}\text{2}}{\text{25}}\text{+}\dfrac{\text{5}}{\text{-8}}\text{+}\dfrac{\text{2}}{\text{-5}}\text{+}\dfrac{\text{1}\text{3}}{\text{25}}\text{=}\text{?}\)\(\text{ }\text{(}\dfrac{\text{9}}{\text{1}\text{6}}\text{+}\dfrac{\text{8}}{\text{-27}}\text{)}\text{+}\text{(}\text{1}\text{+}\dfrac{\text{7}}{\text{16}}\text{+}\dfrac{\text{-}\text{1}\text{9}}{\text{27}}\text{=}\text{?}\)
\(\dfrac{\text{4}\text{2}}{\text{46}}\text{+}\dfrac{\text{2}\text{5}\text{0}}{\text{2}\text{8}\text{6}}\dfrac{\text{-}\text{2}\text{1}}{\text{2}\text{3}\text{2}}\text{+}\dfrac{\text{-}\text{143143}}{\text{143143}}\text{=}\text{?}\)
Mọi người giúp mình với mình sắp thi rồi còn 1 ngãy nữa thôi
a,\(\dfrac{1}{7}\text{x}\dfrac{2}{7}+\dfrac{1}{7}\text{x}\dfrac{5}{7}+\dfrac{6}{7}\) b,\(\dfrac{6}{11}\text{x}\dfrac{4}{9}+\dfrac{6}{11}\text{x}\dfrac{7}{9}-\dfrac{6}{11}\text{x}\dfrac{2}{9}\)
c, \(\dfrac{4}{25}\text{x}\dfrac{5}{8}\text{x}\dfrac{25}{4}\text{x}24\)
`a)1/7xx2/7+1/7xx5/7+6/7`
`=1/7xx(2/7+5/7)+6/7`
`=1/7xx1+6/7`
`=1/7+6/7=1`
`b)6/11xx4/9+6/11xx7/9-6/11xx2/9`
`=6/11xx(4/9+7/9-2/9)`
`=6/11xx9/9`
`=6/11`
Sorry nãy ghi thiếu.
`c)4/25xx5/8xx25/4xx24`
`=(4xx5xx25xx24)/(25xx8xx4)`
`=(4xx5xx24)/(4xx8)`
`=(5xx24)/8`
`=5xx3=15`
a, \(\dfrac{1}{7}.\dfrac{2}{7}+\dfrac{1}{7}.\dfrac{5}{7}+\dfrac{6}{7}\)
\(=\dfrac{1}{7}.\left(\dfrac{2}{7}+\dfrac{5}{7}\right)+\dfrac{6}{7}\)
\(=\dfrac{1}{7}.1+\dfrac{6}{7}\)
\(=\dfrac{1}{7}+\dfrac{6}{7}=1\)
b, \(\dfrac{6}{11}.\dfrac{4}{9}+\dfrac{6}{11}.\dfrac{7}{9}-\dfrac{6}{11}.\dfrac{2}{9}\)
\(=\dfrac{6}{11}.\left(\dfrac{4}{9}+\dfrac{7}{9}-\dfrac{2}{9}\right)\)
\(=\dfrac{6}{11}.1=\dfrac{6}{11}\)
c, \(\dfrac{4}{25}.\dfrac{5}{8}.\dfrac{25}{4}.24\)
\(=\left(\dfrac{4}{25}.\dfrac{25}{4}\right).\left(\dfrac{5}{8}.24\right)\)
\(=1.15=15\)
Tính:
\(\dfrac{1}{2\text{×}5}+\dfrac{1}{5\text{×}8}+\dfrac{1}{8\text{×}11}+...+\dfrac{1}{92\text{×}95}+\dfrac{1}{95\text{×}97}\)
đặt
\(A=\dfrac{1}{2\cdot5}+\dfrac{1}{5\cdot8}+\dfrac{1}{8\cdot11}+..+\dfrac{1}{92\cdot95}+\dfrac{1}{95\cdot97}\)
\(3A=\dfrac{3}{2\cdot5}+\dfrac{3}{5\cdot8}+\dfrac{3}{8\cdot11}+...+\dfrac{3}{92\cdot95}+\dfrac{3}{95\cdot97}\)
\(3A=\dfrac{1}{2}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{11}+...+\dfrac{1}{92}-\dfrac{1}{95}+\dfrac{1}{95}-\dfrac{1}{97}\)
\(3A=\dfrac{1}{2}-\dfrac{1}{97}\\ 3A=\dfrac{95}{194}\\ A=\dfrac{95}{582}\)
\(\dfrac{\text{11× -12 + 11 × -5 }}{\text{19× 17+ 19× 17}}\)\(+ 2\)
Tính giúp em với ak
Ai làm nhanh nhất sẽ tick người đó nhé
= 11.(-12+-5)/19.(17+17)+2 =11.-17/17.34+2 =-1.11.17/17.34 +2 =-11/34 +2 =-11/34+68/34 =57/34
\(\dfrac{11×-12+11×-5}{19×17+19×17}+2\)
\(= \dfrac{11×(-12-5)}{19×(17+17)}+2\)
\(= \dfrac{11×-17}{19×34}+2\)
\(= \dfrac{-187}{646}+2\)
\(= \dfrac{-11}{38}+2\)
\(= \dfrac{65}{38}\)
so sánh các số hữu tỉ sau bằng cách hợp lí:
a) -0,2; \(\dfrac{1}{1000}\)
b) \(\dfrac{\text{13}}{\text{-35}};\dfrac{\text{-11}}{\text{28}}\)
c) \(\dfrac{2022}{-2021};\dfrac{-1995}{1996}\)
d) \(\dfrac{\text{-18}}{\text{13}};\dfrac{\text{181818}}{\text{131313}}\)
Cô làm rồi em nhé:
https://olm.vn/cau-hoi/giup-em-voiii.8161766187032
Giải thích vì sao các phân số sau được viết dưới dạng số thập phân vô hạn tuần hoàn rồi viết chúng dưới dạng đó.
a)\(\dfrac{\text{7}}{\text{12}}\)
b)\(\dfrac{\text{-7}}{\text{125}}\)
c)\(\dfrac{\text{5}}{\text{33}}\)
d)\(\dfrac{\text{-18}}{\text{11}}\)
a: 12 khi phân tích thành nhân tử, có thừa số 3 là thừa số khác 2 và 5 ở trong nên 7/12 viết được dưới dạng số thập phân vô hạn tuần hoàn
So sánh các phân số sau:
a, \(\dfrac{-11}{-32}\) và \(\dfrac{\text{16}}{\text{49}}\)
b, \(\dfrac{\text{- 2020 }}{\text{-2021}}\) và \(\dfrac{\text{-2021}}{\text{2022}}\)
\(\dfrac{-11}{-32}>\dfrac{16}{49}\)
\(\dfrac{-2020}{-2021}>\dfrac{-2021}{2022}\)
1.Tính
\(a,5\text{x}\dfrac{7}{3}\) \(b,\dfrac{13}{4}:7\)
2.Tính
\(a,\dfrac{3}{7}+\dfrac{2}{5}+\dfrac{3}{4}\) \(b,\dfrac{9}{7}-\dfrac{5}{11}\text{x}\dfrac{11}{7}\) \(c,\dfrac{3}{5}\text{x}\dfrac{5}{7}\text{+}\dfrac{4}{7}\) \(d,\dfrac{7}{9}\text{x}\dfrac{2}{5}:\dfrac{3}{11}\) e,\(\dfrac{9}{7}+\dfrac{2}{3}-\dfrac{1}{4}\)
g,\(\dfrac{4}{9}:\dfrac{3}{5}\text{x}\dfrac{2}{11}\) h,\(\dfrac{7}{2}-\dfrac{3}{10}:\dfrac{2}{5}\)
\(a,5x\dfrac{7}{3}=\dfrac{5}{1}x\dfrac{7}{3}=\dfrac{35}{3};b,\dfrac{13}{4}:7=\dfrac{13}{4} :\dfrac{7}{1}=\dfrac{13}{4}x\dfrac{1}{7}=\dfrac{13}{28}\)
\(\dfrac{3}{7}+\dfrac{2}{5}+\dfrac{3}{4}=\dfrac{60}{140}+\dfrac{56}{140}+\dfrac{105}{140}=\dfrac{221}{140}\)
\(\dfrac{9}{7}-\dfrac{5}{11}x\dfrac{11}{7}=\dfrac{9}{7}-\dfrac{5}{7}=\dfrac{4}{7}\)
rút gọn biểu thức B = \(\dfrac{\text{20x - 11}}{\text{x - 2012}}.\dfrac{\text{x(x - 2)}}{\text{1982x}^{\text{2}}+30}-\dfrac{20x-11}{1982x^2+30}:\dfrac{x-2012}{x\left(x-3\right)+2012}\)
\(B=\dfrac{\left(x^2-2x\right)\left(20x-11\right)}{\left(x-2012\right)\left(1982x^2+30\right)}-\dfrac{\left(20x-11\right)\left(x^2-3x+2012\right)}{\left(1982x^2+30\right)\left(x-2012\right)}\left(x\ne2012\right)\\ B=\dfrac{\left(20x-11\right)\left(x^2-2x-x^2+3x-2012\right)}{\left(x-2012\right)\left(1982x^2+30\right)} \\ B=\dfrac{\left(20x-11\right)\left(x-2012\right)}{\left(x-2012\right)\left(1982x^2+30\right)}=\dfrac{20x-11}{1982x^2+30}\)