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\(0,05+5-\dfrac{1}{20}=0,05+5-0,05=5\)
\(\dfrac{6}{15}-\dfrac{7}{8}+3+\dfrac{3}{5}-\dfrac{2}{16}=\dfrac{2}{.5}-\dfrac{7}{8}+3+\dfrac{3}{5}-\dfrac{1}{8}=1-1+3=3\)
a) \(0.05+5-\dfrac{1}{20}=\dfrac{1}{20}+5-\dfrac{1}{20}=5\)
b) \(\dfrac{6}{15}-\dfrac{7}{8}+3+\dfrac{3}{5}-\dfrac{2}{16}=1-1+3=3\)
`#lv`
`-2/5+(-7/10)-9/6`
`=-2/5-7/10-9/6`
`=-4/10-7/10-9/6`
`=-11/10-3/2`
`=-11/10-15/10`
`=-26/10`
`=-13/5`
__
`1/2+(-2/5)-(-2/3)`
`=1/2-2/5+2/3`
`=5/10-4/10+2/3`
`=1/10+2/3`
`=3/30+20/30`
`=23/30`
__
`5/3-3/4+7/6`
`=20/12-9/12+14/12`
`=11/12+14/12`
`=25/12`
__
`-1/5+5/3-3/2`
`=-3/15+25/15-3/2`
`=22/15-3/2`
`=44/30-45/30`
`=-1/30`
__
`1/4-7/8+(-9/10)`
`=2/8-7/8-9/10`
`=-5/8-9/10`
`=-25/40-36/40`
`=-61/40`
__
`5/4+1/2+(-7/12)`
`=15/12+6/12-7/12`
`=21/12-7/12`
`=14/12`
`=7/6`
__
`-5/8-1/3+(-7/6)`
`=-5/8-1/3-7/6`
`=-15/24-8/24-28/24`
`=-52/24`
`=-13/6`
__
`-3/4-7/10+(-5/6)`
`=-3/4-7/10-5/6`
`=-45/60-42/60-50/60`
`=-137/60`
Bài làm
a, (-2/5) + (-7/10) - 9/6 =(-12/30) + (-21/30) - 45/30=(-33/30) - 45/30 = (-78/30)
b,1/2 + (-2/5) - (-2/3) = 15/30 + (-12/30) - (-20/30) = 3/30 - (-20/30) = 23/30
c,5/3 - 3/4 + 7/6 = 40/24 - 18/24 + 28/24 = 22/24 + 28/24 = 50/24 = 25/12
d, (-1/5) + 5/3 - 3/2 = (-6/30) + 50/30 - 45/30 = 44/30 - 45/30 = (-1/30)
e, 1/4 - 7/8 + (-9/10) = 10/40 - 35/40 - 36/40 = (-25/40) - 36/40 = (-61/40)
f, 5/4 +1/2 + (-7/12) = 15/12 + 6/12 - 7/12 = 21/12 - 7/12 = 14/12 = 7/6
g,(-5/8) -1/3 + (-7/6) = (-15/24) - 8/24 - 28/24 = (-23/24) - 28/24 = (-51/24)
k,(-3/4) - 7/10 + (-5/6) = (-45/60) - 42/60 - 50/60 = (-87/60) - 50/60 = (-137/60)
chúc bn học tốt nha
sai thì mn góp ý giúp mk
a) \(4\times\dfrac{1}{4^2}+25\times\left[\dfrac{3^3}{4^3}:\dfrac{5^3}{4^3}\right]:\dfrac{3^3}{2^3}\)
\(=\dfrac{1}{4}+5^2\times\dfrac{3^3}{4^3}\times\dfrac{4^3}{5^3}\times\dfrac{2^3}{3^3}\)
\(=\dfrac{1}{4}+\dfrac{2^3}{5}=\dfrac{1}{4}+\dfrac{8}{5}=\dfrac{37}{20}\)
b) \(2^3+3\times\left(\dfrac{1}{2}\right)^{0-1}+\left[\left(-2\right)^2:\dfrac{1}{2}\right]-8\)
\(=8+3\times\left(2^{-1}\right)^{-1}+2^2\times2-8\)
\(=3\times2+2^3=14\)
Muộn rùi ngủ thôi không mai lớn có một khúc à :v
Bạn nên viết đề bằng công thức toán (biểu tượng $\sum$ góc trái khung soạn thảo) để được hỗ trợ tốt hơn nhé. Viết thế này người đọc đề sẽ rất mệt.
A = \(\dfrac{2}{5}:\dfrac{3}{4}+\dfrac{2}{5}.\dfrac{3}{6}+\dfrac{2}{5}\)
A=\(\dfrac{2}{5}.\dfrac{4}{3}+\dfrac{2}{5}.\dfrac{3}{6}+\dfrac{2}{5}\)
A=\(\dfrac{2}{5}.\left(\dfrac{4}{3}+\dfrac{3}{6}+1\right)\) =\(\dfrac{2}{5}.\dfrac{17}{6}\)= \(\dfrac{17}{5}\)
B = \(\dfrac{5}{21}.\dfrac{4}{11}+\dfrac{7}{11}.\dfrac{5}{21}-\dfrac{2}{3}\)
B =\(\dfrac{5}{21}\left(\dfrac{4}{11}+\dfrac{7}{11}\right)-\dfrac{2}{3}\)
B= \(\dfrac{5}{21}.1-\dfrac{2}{3}\) = \(\dfrac{5}{21}-\dfrac{2}{3}=\dfrac{-3}{7}\)
Ta có :
a, \(\frac{31}{12}-(\frac{2}{5}+x)=\frac{2}{3}\)
\(\Rightarrow\frac{2}{5}+x=\frac{31}{12}-\frac{2}{3}=\frac{23}{12}\)
\(\Rightarrow\frac{23}{12}-\frac{31}{12}=\frac{-8}{12}=\frac{-2}{3}\)
Câu b để mk làm sau
\(a,\dfrac{1}{2}-\dfrac{1}{3}-\left(-\dfrac{5}{4}\right)=\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{5}{4}=\dfrac{1\times6-1\times4+5\times3}{12}=\dfrac{6-4+15}{12}=\dfrac{17}{12}\\ b,\dfrac{5}{4}-\dfrac{1}{2}-\dfrac{7}{8}=\dfrac{5\times2-1\times4-7}{8}=\dfrac{10-4-7}{8}=-\dfrac{1}{8}\\ c,\dfrac{1}{5}-\dfrac{1}{2}+\dfrac{9}{10}=\dfrac{1\times2-1\times5+9}{10}=\dfrac{2-5+9}{10}=\dfrac{6}{10}=\dfrac{3}{5}\\ d,\dfrac{5}{4}-\dfrac{1}{3}+\dfrac{7}{6}=\dfrac{5\times3-1\times4+7\times2}{12}=\dfrac{15-4+14}{12}=\dfrac{25}{12}\)
Tính:
\(\frac{2}{3}+\frac{3}{4}=\frac{8}{12}+\frac{9}{12}=\frac{17}{12}\)
\(\frac{1}{5}+\frac{3}{2}=\frac{2}{10}+\frac{15}{10}=\frac{17}{10}\)
\(\frac{6}{5}-\frac{2}{3}=\frac{18}{15}-\frac{10}{15}=\frac{8}{15}\)
\(\frac{7}{2}-\frac{3}{4}=\frac{14}{4}-\frac{3}{4}=\frac{11}{4}\)
\(1\frac{2}{5}+\frac{7}{2}=\frac{7}{5}+\frac{7}{2}=\frac{14}{10}+\frac{35}{10}=\frac{49}{10}\)
\(2\frac{1}{8}-\frac{5}{6}=\frac{17}{8}-\frac{5}{6}=\frac{51}{24}-\frac{20}{24}=\frac{31}{24}\)
\(0,75+2\frac{1}{3}=\frac{3}{4}+\frac{7}{3}=\frac{9}{12}+\frac{28}{12}=\frac{37}{12}\)
\(1-\frac{1}{4}-0,25=1-\frac{1}{4}-\frac{1}{4}=\frac{4}{4}-\frac{1}{4}-\frac{1}{4}=\frac{2}{4}=\frac{1}{2}\)
\(\frac{11}{2}-\frac{5}{3}+\frac{7}{4}=\frac{66}{12}-\frac{20}{12}+\frac{21}{12}=\frac{67}{12}\)
\(\frac{5}{6}+1\frac{2}{3}-\frac{1}{4}=\frac{5}{6}+\frac{5}{3}-\frac{1}{4}=\frac{10}{12}+\frac{20}{12}-\frac{3}{12}=\frac{27}{12}=\frac{9}{4}\)
\(0,5+2\frac{3}{5}-\frac{5}{4}=\frac{1}{2}+\frac{13}{5}-\frac{5}{4}=\frac{10}{20}+\frac{52}{20}-\frac{25}{20}=\frac{37}{20}\)
\(3\frac{1}{2}-\frac{5}{6}+1,2=\frac{7}{2}-\frac{5}{6}+\frac{6}{5}=\frac{105}{30}-\frac{25}{30}+\frac{36}{30}=\frac{116}{30}=\frac{58}{15}\)
\(\frac{1}{3}+2\frac{1}{4}=\frac{1}{3}+\frac{9}{4}=\frac{4}{12}+\frac{27}{12}=\frac{31}{12}\)
\(\frac{7}{2}+\frac{3}{4}+\frac{7}{12}=\frac{42}{12}+\frac{9}{12}+\frac{7}{12}=\frac{58}{12}=\frac{29}{6}\)
\(2-\frac{4}{9}-\frac{1}{6}=\frac{36}{18}-\frac{8}{18}-\frac{3}{18}=\frac{25}{18}\)
Chúc bạn hok tốt !!! ღℓїŋɦ✿şʉŋღ
Ta có:A=2+22+23+...+220
=>2A=2(2+22+23+...+220)
2A=4+23+24+...+221
=>2A-A=(4+23+24+...+221)-(2+22+23+...+220)
A=221-2
A= 2.( 2+ 2+ 3+ 4+ 5+ 6+ 7+8 +9 + 10= 11+ 12+ 13+ 14+15+ 16+ 17+ 18+ 19+ 20)
A=2.211
A= 422
B= 5.(1+ 5+ 2+ 3+ 4+ 5+ 6+ 7+ 8+ 9+..........+30)
B= 5. 470
B= 2350