a.\(4+\dfrac{5}{9}\) b.\(\dfrac{8}{3}-2\) c.\(\dfrac{5}{12}\times\dfrac{4}{15}\) d.\(5:\dfrac{15}{8}\)
a. 4+\(\dfrac{5}{9}\) b. \(\dfrac{8}{3}\)\(-2\) c. \(\dfrac{5}{12}\times\dfrac{4}{15}\) d.\(5:\dfrac{15}{8}\)
a,\(4+\dfrac{5}{9}=\dfrac{4}{1}+\dfrac{5}{9}=\dfrac{36}{9}+\dfrac{5}{9}=\dfrac{41}{9}\)
b,\(\dfrac{8}{3}-2=\dfrac{8}{3}-\dfrac{2}{1}=\dfrac{8}{3}-\dfrac{6}{3}=\dfrac{2}{3}\)
c,\(\dfrac{5}{12}x\dfrac{4}{15}=\dfrac{20}{180}=\dfrac{2}{18}=\dfrac{1}{6}\)
d,\(5:\dfrac{15}{8}=\dfrac{5x8}{15}=\dfrac{40}{15}=\dfrac{8}{3}\)
Rút gọn rồi tính:
a) \(\dfrac{3}{9}\times\dfrac{5}{4}\) b) \(\dfrac{10}{15}\times\dfrac{3}{5}\) c) \(\dfrac{5}{8}\times\dfrac{4}{12}\) d) \(\dfrac{9}{27}\times\dfrac{3}{21}\)
a: \(\dfrac{3}{9}\times\dfrac{5}{4}=\dfrac{5}{4}\times\dfrac{1}{3}=\dfrac{5\times1}{4\times3}=\dfrac{5}{12}\)
b: \(\dfrac{10}{15}\times\dfrac{3}{5}=\dfrac{3}{5}\times\dfrac{2}{3}=\dfrac{3\times2}{5\times3}=\dfrac{2}{5}\)
c: \(\dfrac{5}{8}\times\dfrac{4}{12}=\dfrac{5}{8}\times\dfrac{1}{3}=\dfrac{5}{3\times8}=\dfrac{5}{24}\)
d: \(\dfrac{9}{27}\times\dfrac{3}{21}=\dfrac{1}{7}\times\dfrac{1}{3}=\dfrac{1\times1}{7\times3}=\dfrac{1}{21}\)
Rút gọn rồi tính.
a) \(\dfrac{2}{4}\times\dfrac{9}{5}\) b) \(\dfrac{13}{8}\times\dfrac{5}{15}\) c) \(\dfrac{3}{9}\times\dfrac{6}{12}\)
a) \(\dfrac{2}{4}\times\dfrac{9}{5}=\dfrac{1}{2}\times\dfrac{9}{5}=\dfrac{1\times9}{2\times5}=\dfrac{9}{10}\)
b) \(\dfrac{13}{8}\times\dfrac{5}{15}=\dfrac{13}{8}\times\dfrac{1}{3}=\dfrac{13}{24}\)
c) \(\dfrac{3}{9}\times\dfrac{6}{12}=\dfrac{1}{3}\times\dfrac{1}{2}=\dfrac{1}{3\times2}=\dfrac{1}{6}\)
a: =18/20=9/10
b: \(=\dfrac{13\cdot5}{8\cdot15}=\dfrac{13}{8}\cdot\dfrac{1}{3}=\dfrac{13}{24}\)
c: \(=\dfrac{1}{3}\cdot\dfrac{1}{2}=\dfrac{1}{6}\)
Tính (Tính hợp lí nếu có thể)
a) \(\dfrac{-7}{12}\)-\(\dfrac{3}{36}\)
b) (4-\(\dfrac{5}{12}\)):2+\(\dfrac{5}{24}\)
c) \(\dfrac{8}{9}\)+\(\dfrac{1}{9}\).\(\dfrac{2}{13}\)+\(\dfrac{1}{9}\).\(\dfrac{11}{13}\)
d) \(\dfrac{3}{4}\).\(\dfrac{8}{9}\).\(\dfrac{15}{16}\). ... .\(\dfrac{9999}{10000}\)
e) \(\dfrac{3}{1.4}\)+\(\dfrac{3}{4.7}\)+\(\dfrac{3}{7.10}\)+...+\(\dfrac{3}{97.100}\)
*Lưu ý: Mong các anh chị trình bày chi tiết để em có thể hiểu bài, em xin các anh chị đừng viết mỗi kết quả xong em chả biết một cái gì ;-;
a: =-21/36-3/36=-24/36=-2/3
b: =43/12*1/2+5/24=43/24+5/24=2
c: =8/9+1/9=1
e: =1-1/4+1/4-1/7+...+1/97-1/100
=1-1/100=99/100
a) \(\dfrac{-2}{15}\times x=\dfrac{-2}{7}\) b) \(\dfrac{7}{-5}\times x=-3\) c) \(-\dfrac{4}{9}x=\dfrac{1}{2}\) d) \(\dfrac{8}{3}\div x=\dfrac{-3}{8}\)
e) \(x\div\dfrac{3}{-4}=-12\) f) \(\left(-1\right)\div x=\dfrac{-3}{7}+\dfrac{4}{5}\) g)\(\dfrac{4}{11}x-\dfrac{1}{3}=\dfrac{2}{5}\) i) \(\dfrac{-6}{7}-\dfrac{1}{5}x=-4\)
j) \(\dfrac{1}{2}+\dfrac{2}{3}\div7=\dfrac{-1}{3}\) k) \(\dfrac{-5}{2}+x\div7=\dfrac{-1}{3}\) L) \(\dfrac{-3}{2}-\dfrac{1}{4}\div x=-1\)
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
a) \(\dfrac{-21}{15}\).\(\dfrac{-10}{14}\) b)\(\left(-\dfrac{2}{3}\right)^2\) c)\(\dfrac{-3}{4}\).\(\dfrac{-4}{5}\).\(\dfrac{16}{9}\) d)\(\dfrac{-8}{3}\).\(\dfrac{5}{6}\) e)\(\dfrac{16}{30}\).\(\dfrac{5}{12}\) f) \(\dfrac{13}{30}\).\(\dfrac{-1}{5}\) g)\(\dfrac{2}{21}\).\(\dfrac{3}{28}\) h)\(\left(\dfrac{-3}{4}\right)^3\)
`a, -21/15 . (-10)/14 = 210/210=1`
`b, (-2/3)^2= 4/9`
`c, (-3)/4 . (-4)/5 . 16/9= 192/180=16/15`
`d, (-8)/3 . 5/6= -40/18=-20/9`
`e, 16/30 . 5/12= 8/15 . 5/12=40/180=2/9`
`f, 13/30 . (-1)/5= -13/150`
`g, 2/21 . 3/28= 6/588= 1/98`
`h, (-3/4)^3= -27/64`
Tính:
a) \(\dfrac{-5}{9}\)\(+\dfrac{8}{15}+\dfrac{-2}{11}+\dfrac{4}{-9}+\dfrac{7}{15}\)
b)\(\left(\dfrac{-5}{12}+\dfrac{6}{11}\right)+\left(\dfrac{7}{17}+\dfrac{5}{11}+\dfrac{5}{12}\right)\)
c) A= \(49\dfrac{8}{23}-\left(5\dfrac{7}{32}+14\dfrac{8}{23}\right)\)
d) C= \(\dfrac{-3}{7}.\dfrac{5}{9}+\dfrac{4}{9}.\dfrac{-3}{7}+2\dfrac{3}{7}\)
a) \(\dfrac{-5}{9}+\dfrac{8}{15}+\dfrac{-2}{11}+\dfrac{4}{-9}+\dfrac{7}{15}\)
=\(\left(\dfrac{-5}{9}+\dfrac{-4}{9}\right)+\left(\dfrac{8}{15}+\dfrac{7}{15}\right)+\dfrac{-2}{11}\)
=\(\left(-1\right)+1+\dfrac{-2}{11}\)
=\(\dfrac{-2}{11}\)
b) \(\left(\dfrac{-5}{12}+\dfrac{6}{11}\right)+\left(\dfrac{7}{17}+\dfrac{5}{11}+\dfrac{5}{12}\right)\)
=\(\dfrac{-5}{12}+\dfrac{6}{11}+\dfrac{7}{17}+\dfrac{5}{11}+\dfrac{5}{12}\)
=\(\left(\dfrac{-5}{12}+\dfrac{5}{12}\right)+\left(\dfrac{6}{11}+\dfrac{5}{11}\right)+\dfrac{7}{17}\)
=\(0+0+\dfrac{7}{17}\)
=\(\dfrac{7}{17}\)
c) A= \(49\dfrac{8}{23}-\left(5\dfrac{7}{32}+14\dfrac{8}{23}\right)\)
A=\(49\dfrac{8}{23}-5\dfrac{7}{32}-14\dfrac{8}{23}\)
A=\(\left(49\dfrac{8}{23}-14\dfrac{8}{23}\right)-5\dfrac{7}{32}\)
A=\(35-5\dfrac{7}{32}\)
A=\(35-\dfrac{167}{32}=\dfrac{953}{32}\)
d) C=\(\dfrac{-3}{7}.\dfrac{5}{9}+\dfrac{4}{9}.\dfrac{-3}{7}+2\dfrac{3}{7}\)
C=\(\dfrac{-3}{7}.\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+\dfrac{17}{7}\)
C=\(\dfrac{-3}{7}.1+\dfrac{17}{7}\)
C=\(\dfrac{-3}{7}+\dfrac{17}{7}=2\)
a, `(-5)/9+8/15+(-2)/11+4/(-9)+7/15`
`=-5/9+8/15-2/11-4/9+7/15`
`=(-5/9-4/9)+(8/15+7/15)-2/11`
`=-9/9+15/15-2/11`
`=-1+1-2/11`
`=-2/11`
b, `((-5)/12+6/11)+(7/17+5/11+5/12)`
`=-5/12+6/11+7/17+5/11+5/12`
`=(-5/12+5/12)+(6/11+5/11)+7/17`
`=0+11/11+7/17`
`=1+7/17`
`=17/17+7/17`
`=24/17`
c, `A=49 8/23 - (5 7/32 + 14 8/23)`
`A=49 8/23 - 5 7/32 - 14 8/23`
`A=(49 8/23 - 14 8/23)-5 7/32`
`A=35 - 167/32`
`A=953/32`
d, `C=(-3)/7.5/9+4/9.(-3)/7+2 3/7`
`C=-3/7 . 5/9-4/9 . 3/7+17/7`
`C=-3/7.(5/9+4/9)+17/7`
`C=-3/7 . 1+17/7`
`C=2`
a) Ta có: \(\dfrac{-5}{9}+\dfrac{8}{15}+\dfrac{-2}{11}+\dfrac{-4}{9}+\dfrac{7}{15}\)
\(=\left(\dfrac{-5}{9}+\dfrac{-4}{9}\right)+\left(\dfrac{8}{15}+\dfrac{7}{15}\right)-\dfrac{2}{11}\)
\(=-1+1-\dfrac{2}{11}\)
\(=-\dfrac{2}{11}\)
b) Ta có: \(\left(\dfrac{-5}{12}+\dfrac{6}{11}\right)+\left(\dfrac{7}{11}+\dfrac{5}{11}+\dfrac{5}{12}\right)\)
\(=\left(\dfrac{-5}{12}+\dfrac{5}{12}\right)+\left(\dfrac{6}{11}+\dfrac{7}{11}+\dfrac{5}{11}\right)\)
\(=\dfrac{18}{11}\)
c) Ta có: \(A=49\dfrac{8}{23}-\left(5\dfrac{7}{32}+14\dfrac{8}{23}\right)\)
\(=49+\dfrac{8}{23}-14-\dfrac{8}{23}-5-\dfrac{7}{32}\)
\(=30-\dfrac{7}{32}=\dfrac{953}{32}\)
\(\dfrac{-1}{3}.\dfrac{2}{5}\)
\(\dfrac{-3}{7}.\dfrac{4}{15}\)
\(\dfrac{-9}{3}.\dfrac{15}{27}\)
\(\dfrac{-5}{6}.\)( -12 )
\(\dfrac{-12}{4}.\dfrac{8}{9}\)
\(-3.\dfrac{7}{6}\)
\(\dfrac{-15}{9}.\dfrac{27}{5}\)
\(-9.\dfrac{4}{27}\)
-2/15
-4/35
-5/3
10
-8/3
-7/2
-9
-4/3
Chúc em học giỏi
\(=\dfrac{-2}{15}\\ =\dfrac{-4}{35}\\ =-1\\ =10\\ =\dfrac{-8}{3}\\ =-7\\ =-9\\ =\dfrac{-4}{3}\)
Tính:
a) \(\dfrac{12}{17}:6\); \(16:\dfrac{8}{11}\); \(9:\dfrac{3}{5}\times\dfrac{4}{15}\)
b) \(72:45\) \(281,6:8\) \(300,72:53,7\)
\(15:50\) \(912,8:28\) \(0,162:0,36\)
a, 1. \(\dfrac{2}{17}\)
2. \(22\)
3. 4
b,
1. \(\dfrac{8}{5}\)
2. \(\dfrac{176}{5}\)
3. \(\dfrac{28}{5}\)
4. \(\dfrac{3}{10}\)
5. \(\dfrac{163}{5}\)
6. \(\dfrac{9}{20}\)
a) \(\dfrac{12}{17}:6=\dfrac{12}{17}\cdot\dfrac{1}{6}=\dfrac{2}{17}\)
a) \(16:\dfrac{8}{11}=16\cdot\dfrac{11}{8}=22\)