TÍNH : 2/3/19+1/5-5/3/19+(-5/3/19-6/5)
tính
2/2/19+1/5-5/3/19+(-5/3/19-6/5)
2/2/19+1/5-5/3/19+(-5/3/19-6/5)
=2/2/19+(1/5-6/5)+(5/3/19-5/3/19)
=19-1+0=18
Tính hợp lý:
a) ( -5/6 + 2/5) : 3/8 + ( 4/5 - 11/30) : 3/8
b) (-3/4 + 2/5) : 3/7 + ( 3/5 + -1/4) : 3/7
c)-13/18 . 5/8 + -5/18 . 2/9 + -13/18 . 3/8 + -5/18 . 7/9
d) -11/19 . 4/9 + -8/19 . 3/7 + -11/19 . 5/9 + -9/19 . 4/7
a: \(\left(-\dfrac{5}{6}+\dfrac{2}{5}\right):\dfrac{3}{8}+\left(\dfrac{4}{5}-\dfrac{11}{30}\right):\dfrac{3}{8}\)
\(=\left(-\dfrac{5}{6}+\dfrac{2}{5}\right)\cdot\dfrac{8}{3}+\left(\dfrac{4}{5}-\dfrac{11}{30}\right)\cdot\dfrac{8}{3}\)
\(=\dfrac{8}{3}\left(-\dfrac{5}{6}+\dfrac{2}{5}+\dfrac{4}{5}-\dfrac{11}{30}\right)\)
\(=\dfrac{8}{3}\cdot\dfrac{-25+36-11}{30}\)
=0
b: \(\left(-\dfrac{3}{4}+\dfrac{2}{5}\right):\dfrac{3}{7}+\left(\dfrac{3}{5}+\dfrac{-1}{4}\right):\dfrac{3}{7}\)
\(=\left(-\dfrac{3}{4}+\dfrac{2}{5}\right)\cdot\dfrac{7}{3}+\left(\dfrac{3}{5}-\dfrac{1}{4}\right)\cdot\dfrac{7}{3}\)
\(=\dfrac{7}{3}\left(-\dfrac{3}{4}+\dfrac{2}{5}+\dfrac{3}{5}-\dfrac{1}{4}\right)\)
\(=\dfrac{7}{3}\cdot0=0\)
c: \(\dfrac{-13}{18}\cdot\dfrac{5}{8}+\dfrac{-5}{18}\cdot\dfrac{2}{9}+\dfrac{-13}{18}\cdot\dfrac{3}{8}+\dfrac{-5}{18}\cdot\dfrac{7}{9}\)
\(=\left(-\dfrac{13}{18}\cdot\dfrac{5}{8}+\dfrac{-13}{18}\cdot\dfrac{3}{8}\right)+\left(-\dfrac{5}{18}\cdot\dfrac{2}{9}+\dfrac{-5}{18}\cdot\dfrac{7}{9}\right)\)
\(=-\dfrac{13}{18}\left(\dfrac{5}{8}+\dfrac{3}{8}\right)+\dfrac{-5}{18}\left(\dfrac{2}{9}+\dfrac{7}{9}\right)\)
\(=-\dfrac{13}{18}-\dfrac{5}{18}=-\dfrac{18}{18}=-1\)
d: Sửa đề: \(\dfrac{-11}{19}\cdot\dfrac{4}{9}+\dfrac{-8}{19}\cdot\dfrac{3}{7}+\dfrac{-11}{19}\cdot\dfrac{5}{9}+\dfrac{-8}{19}\cdot\dfrac{4}{7}\)
\(=\left(-\dfrac{11}{19}\cdot\dfrac{4}{9}+\dfrac{-11}{19}\cdot\dfrac{5}{9}\right)+\left(\dfrac{-8}{19}\cdot\dfrac{3}{7}+\dfrac{-8}{19}\cdot\dfrac{4}{7}\right)\)
\(=-\dfrac{11}{19}\left(\dfrac{4}{9}+\dfrac{5}{9}\right)+\dfrac{-8}{19}\left(\dfrac{3}{7}+\dfrac{4}{7}\right)\)
\(=-\dfrac{11}{19}-\dfrac{8}{19}=-\dfrac{19}{19}=-1\)
\(a.\left(-\dfrac{5}{6}+\dfrac{2}{5}\right):\dfrac{3}{8}+\left(\dfrac{4}{5}-\dfrac{11}{30}\right):\dfrac{3}{8}\)
\(=\left(-\dfrac{13}{30}\right):\dfrac{3}{8}+\dfrac{13}{30}:\dfrac{3}{8}\)
\(=\left[\left(-\dfrac{13}{30}+\dfrac{13}{30}\right)\right]:\dfrac{3}{8}\)
\(=0:\dfrac{3}{8}=0\)
\(b.\left(-\dfrac{3}{4}+\dfrac{2}{5}\right):\dfrac{3}{7}+\left(\dfrac{3}{5}+-\dfrac{1}{4}\right):\dfrac{3}{7}\)
\(=\left(-\dfrac{7}{20}\right):\dfrac{3}{7}+\dfrac{7}{20}:\dfrac{3}{7}\)
\(=\left[\left(-\dfrac{7}{20}+\dfrac{7}{20}\right)\right]:\dfrac{3}{7}=0:\dfrac{3}{7}=0\)
\(c.-\dfrac{13}{18}.\dfrac{5}{8}+-\dfrac{5}{18}.\dfrac{2}{9}+-\dfrac{13}{18}.\dfrac{3}{8}+-\dfrac{5}{18}.\dfrac{7}{9}\)
\(=\left(\dfrac{5}{8}+\dfrac{3}{8}\right).-\dfrac{13}{18}+\left(\dfrac{2}{9}+\dfrac{7}{9}\right).-\dfrac{5}{18}\)
\(=1.-\dfrac{13}{18}+1.-\dfrac{5}{18}=-\dfrac{13}{18}+-\dfrac{5}{18}=-1\)
\(d.-\dfrac{11}{19}.\dfrac{4}{9}+\dfrac{-8}{19}.\dfrac{3}{7}+-\dfrac{11}{19}.\dfrac{5}{9}+-\dfrac{9}{19}.\dfrac{4}{7}\)
\(=\left(\dfrac{4}{9}+\dfrac{5}{9}\right).-\dfrac{11}{19}+-\dfrac{24}{133}+-\dfrac{36}{133}\)
\(=-\dfrac{11}{19}+-\dfrac{60}{133}=-\dfrac{137}{133}\)
1 Tính
a.11/4×(-0,4)×-1,6×11/4
b.6/19×-7/11+6/19×-4/19×-4/11+13/19
c.2/5×3/7+-3/7×3/5+3/7
d.2/3×5+2×5/7+2/7×9+...+2/97×99
d)\(\frac{2}{3.5}+\frac{2}{5.7}+....+\frac{2}{97.99}\)
\(=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+....+\frac{1}{97}-\frac{1}{99}\)
\(=\frac{1}{3}-\frac{1}{99}\)
\(=\frac{32}{99}\)
a) 11/4x(-0,4)x-1,6x11/4
= -1,1 x-1,6x11/4
= 1,76x11/4
= 4,48
b) 6/19x-7/11+6/19x-4/19x-4/11+13/19
= -42/209+96/3971+13/19
= -702/3971+13/19
= 2015/3971
c) 2/5x3/7+-3/7x3/5+3/7
= 3/7x(2/5+3/5+1)
= 3/7x(1+1)
= 3/7x2
= 6/7
d) 2/3x5+2x5/7+2/7x9+....+2/97x99
= 1/3-1/5+1/5-1/7+1/7-1/9+......+1/97-1/99
= 1/3-1/99
= 32/99
d)=1/3-1/5+1/5-1/7+....+1/97-1/99
=1/3-1/99
=32/99
Thực hiện phép tính:
1, -3/4+ ( 3- 1/4 ) - ( 5/4- 9/2 )
2, -5/7. 13/19+ -5/7. 6/19+ 5/7
3, 2/5- 2/5. 8/3- 2/5. 5/8
1: \(=-\dfrac{3}{4}+3-\dfrac{1}{4}-\dfrac{5}{4}+\dfrac{9}{2}=-\dfrac{9}{4}+3+\dfrac{9}{2}=\dfrac{-9+12+18}{4}=\dfrac{21}{4}\)
2: \(=\dfrac{-5}{7}\left(\dfrac{13}{19}+\dfrac{6}{19}\right)+\dfrac{5}{7}=\dfrac{-5}{7}+\dfrac{5}{7}=0\)
3: \(=\dfrac{2}{5}\left(1-\dfrac{8}{3}-\dfrac{5}{8}\right)=\dfrac{2}{5}\cdot\dfrac{-55}{24}=\dfrac{-11}{12}\)
Thực hiện phép tính:
1, -3/4+ ( 3- 1/4 ) - ( 5/4- 9/2 )
2, -5/7. 13/19+ -5/7. 6/19+ 5/7
3, 2/5- 2/5. 8/3- 2/5. 5/8
Thực hiện phép tính:
1, -3/4+ ( 3- 1/4 ) - ( 5/4- 9/2 )
2, -5/7. 13/19+ -5/7. 6/19+ 5/7
3, 2/5- 2/5. 8/3- 2/5. 5/8
Thực hiện phép tính(tính hợp lí nếu có thể)
4/5+(-5)/4 -1/3+2/5-5/6 2/3-5/7.14/25 (2/5-5/6):8/15-(-1)^2
-3/13+(-7)/17+(-5)/19+(-10)/13+24/17+(-14)/19
\(\dfrac{4}{5}\)+\(\dfrac{-5}{4}\)=\(\dfrac{0}{4}\)
\(\dfrac{-1}{3}\)+\(\dfrac{2}{5}-\dfrac{5}{6}\)=\(\dfrac{-10}{30}+\dfrac{12}{30}-\dfrac{25}{30}\)=\(\dfrac{-23}{30}\)
\(\dfrac{2}{3}-\dfrac{5}{7}.\dfrac{14}{25}\)=\(\dfrac{2}{3}-\dfrac{2}{5}\)=\(\dfrac{10}{15}-\dfrac{6}{15}\)=\(\dfrac{4}{15}\)
a: \(=\dfrac{16-25}{20}=\dfrac{-9}{20}\)
b: \(=\dfrac{-10}{30}+\dfrac{12}{30}-\dfrac{25}{30}=-\dfrac{23}{30}\)
c: \(=\dfrac{2}{3}-\dfrac{1}{5}\cdot2=\dfrac{2}{3}-\dfrac{2}{5}=\dfrac{10-6}{15}=\dfrac{4}{15}\)
d: \(=\dfrac{12-25}{30}\cdot\dfrac{15}{8}-1=\dfrac{-13}{16}-1=\dfrac{-29}{16}\)
e: \(=\dfrac{-3}{13}-\dfrac{10}{13}-\dfrac{7}{17}+\dfrac{24}{17}-\dfrac{5}{19}-\dfrac{14}{19}=-1\)
1 .Tính.
a,3/4 +5/2 b,3+6/11 c,2-5/7 d,11/3-2
Lưu ý tính rõ ra
2.Tính thuận tiện
a,13/19+18/19+17/19 b,3/5+3/16+13+16
Tính rõ ra
3.chu vi hình chữ nhật là 4 m chiều dài là 5/6 .Tính chiều rộng
1.
\(a,\dfrac{3}{4}+\dfrac{5}{2}=\dfrac{3}{4}+\dfrac{10}{4}=\dfrac{13}{4}\)
\(b,3+\dfrac{6}{11}+\dfrac{33}{11}+\dfrac{6}{11}=\dfrac{39}{11}\)
\(c,2-\dfrac{5}{7}=\dfrac{14}{7}-\dfrac{5}{7}=\dfrac{9}{7}\)
\(\dfrac{11}{3}-2=\dfrac{11}{3}-\dfrac{6}{3}=\dfrac{5}{3}\)
2.
\(a,\dfrac{13}{19}+\dfrac{18}{19}+\dfrac{17}{19}=\dfrac{13}{19}+\dfrac{17}{19}+\dfrac{18}{19}=\dfrac{30}{19}+\dfrac{18}{19}=\dfrac{48}{19}\)
\(b,\dfrac{3}{5}+\dfrac{3}{16}+13+16=\dfrac{63}{80}+29=\dfrac{2383}{80}\)
3.
Nửa chu vi :
\(4:2=2\left(m\right)\)
Chiều rộng :
\(2-\dfrac{5}{6}=\dfrac{7}{6}\left(m\right)\)
1)
a) 3/4+10/4= 13/4
b) 3/1+6/11= 33/11+6/11= 39/11
c) 2/1-5/7= 14/7-5/7= 9/7
d) 11/3-2/1= 11/3-6/3= 5/3
3) Nữa chu vi là
4:2= 2 (m)
Chiều rộng là
2-5/6= 7/6(m)
\(1,\\ a,\dfrac{3}{4}+\dfrac{5}{2}=\dfrac{3}{4}+\dfrac{10}{4}=\dfrac{13}{4}\\ b,3+\dfrac{6}{11}=\dfrac{33}{11}+\dfrac{6}{11}=\dfrac{39}{11}\\ c,2-\dfrac{5}{7}=\dfrac{14}{7}-\dfrac{5}{7}=\dfrac{9}{7}\\ d,\dfrac{11}{3}-2=\dfrac{11}{3}-\dfrac{6}{3}=\dfrac{5}{3}\\ 2,\\ a,\dfrac{13}{19}+\dfrac{18}{19}+\dfrac{17}{19}=\dfrac{13+18+17}{19}=\dfrac{48}{49}\\ b,\dfrac{3}{5}+\dfrac{3}{16}+13+16=\dfrac{48}{80}+\dfrac{15}{80}+\dfrac{1040}{80}+\dfrac{1280}{80}=\dfrac{2383}{80}\)
3, Chiều rộng hcn là:
`4:2- 5/6= 7/6`(m)
Đáp số: `7/6`m
Tính nhanh nếu có thể: b)B=5/2 + 6/-11 + 3/8 - 7/2 + 6/8 + -5/11 c)C=4/3 + 3/5 +7/3 + 2/5 - -1/3 d)D=-5/6 . 4/19 + -7/12 . 4/19 - 40/57 e)E=1/3 . 4/5 + 1/-3 . 9/5 + 2/3
b: \(B=\dfrac{5}{2}-\dfrac{7}{2}+\dfrac{3}{8}+\dfrac{6}{8}+\dfrac{-6}{11}-\dfrac{5}{11}=-2-1+\dfrac{9}{8}=\dfrac{9}{8}-3=-\dfrac{15}{8}\)
c: \(C=\left(\dfrac{4}{3}+\dfrac{7}{3}+\dfrac{1}{3}\right)+\left(\dfrac{2}{5}+\dfrac{3}{5}\right)=4+1=5\)
d: \(D=\dfrac{4}{19}\left(\dfrac{-5}{6}-\dfrac{7}{12}\right)-\dfrac{40}{57}\)
\(=\dfrac{4}{19}\cdot\dfrac{-17}{12}-\dfrac{40}{57}=-1\)
e: \(E=\dfrac{1}{3}\left(\dfrac{4}{5}-\dfrac{9}{5}\right)+\dfrac{2}{3}=\dfrac{2}{3}-\dfrac{1}{3}=\dfrac{1}{3}\)