a) 7/15-(2/15-12/18)
=7/15-2/15+2/3
=5/15+2/3
=1/3+2/3
=1
b)(7/41- 4/9) - (3/19 + 7/41) + (4/9 - 16/19)
=7/41 - 4/9 - 3/19 - 7/41 + 4/9 + 16/19
=(7/41 - 7/41) - (4/9 - 4/9) - (3/19 + 16/19)
= -1
b) 7/41 - 4/9 - 3/19 - 7/41 + 4/9 + 16/19
= (7/41 - 7/41 ) - (4/9 - 4/9 ) + ( 3/19 + 16/19 )
= 0 - 0 + 1
= 1
Bài 1 : Thực hiện phép tính ( tính hợp lý nếu có thể )
a ) \(\dfrac{1}{12}+\dfrac{3}{4}\)
b ) \(\dfrac{-4}{7}.1\dfrac{1}{2}\)
c )\(\dfrac{7}{9}+\left(\dfrac{2}{3}+\dfrac{-7}{9}\right)\)
d )\(\dfrac{2}{3}-\dfrac{1}{3}:\dfrac{3}{4}\)
e )\(\dfrac{-7}{25}.\dfrac{11}{13}+\dfrac{-7}{25}.\dfrac{2}{13}\)
g )\(2\dfrac{2}{5}.0,25-\left(\dfrac{11}{20}+75\%\right):\dfrac{13}{5}\)
Bài 1. Thực hiện phép tính:
a) |5.0,6+\(\dfrac{2}{3}\)|- \(\dfrac{1}{3}\)
b)(0,25 - 1\(\dfrac{1}{4}\)) : 5 - \(\dfrac{1}{5}\).(-3)\(^2\)
c)\(\dfrac{14}{17}.\dfrac{7}{5}-\dfrac{-3}{17}:\dfrac{5}{7}\)
d)\(\dfrac{7}{16}+\dfrac{-9}{25}+\dfrac{9}{16}+\dfrac{-16}{25}\)
e)\(\dfrac{5}{6}+2\sqrt{\dfrac{4}{9}}\)
làm đầy đủ theo các bước nhé
Tìm x biết :
a) \(^{\dfrac{4}{9}+x=\dfrac{5}{3}}\)
b)\(\dfrac{3}{4}.x=\dfrac{-1}{2}\)
c) \(\dfrac{3}{7}+\dfrac{5}{7}:x=\dfrac{1}{3}\)
d)\(3\dfrac{1}{4}:\left|2x-\dfrac{5}{12}\right|=\dfrac{39}{16}\)
tính nhanh
\(\dfrac{5}{7}.\dfrac{-4}{19}+\dfrac{-15}{7}.\dfrac{5}{19}\)
Chứng tỏ rằng:
a) \(S=\dfrac{1}{5}+\dfrac{1}{13}+\dfrac{1}{14}+\dfrac{1}{15}+\dfrac{1}{61}+\dfrac{1}{62}+\dfrac{1}{63}< \dfrac{1}{2}\)
b) \(S=\dfrac{1}{41}+\dfrac{1}{42}+...+\dfrac{1}{80}>\dfrac{7}{12}\)
c) \(S=\dfrac{1}{2}+\dfrac{1}{2^2}+\dfrac{1}{2^3}+...+\dfrac{1}{2^{20}}< 1\)
d) \(\dfrac{49}{100}< S=\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+...+\dfrac{1}{99^2}< 1\)
Các bạn giải ra từng bước dùm mik nha
Thanks m.n
Thực hiện phép tính ( tính nhanh nếu có thể)
a)3\(\dfrac{14}{19}\) +\(\dfrac{13}{17}\)+\(\dfrac{35}{43}\)+ 6\(\dfrac{5}{19}\) + \(\dfrac{8}{43}\)
b) \(\dfrac{-5}{7}\) . \(\dfrac{2}{11}\) + \(\dfrac{-5}{7}\) . \(\dfrac{9}{11}\) + 1\(\dfrac{5}{7}\)
c) 11\(\dfrac{3}{13}\) - ( 2\(\dfrac{4}{7}\) + 5\(\dfrac{3}{13}\))
d) \(\dfrac{2}{7}\) . 5\(\dfrac{1}{4}\) - \(\dfrac{2}{7}\) . 3\(\dfrac{1}{4}\)
Thực hiện phép tính : \(\dfrac{3}{2}-\dfrac{5}{6}-\dfrac{9}{20}-\dfrac{13}{42}+\dfrac{11}{30}+\dfrac{15}{56}+\dfrac{7}{12}\)
các bạn làm cả lời giải ra nhé mk hơi lazy nên các bạn làm hộ nhé mk sẽ tk
so sánh các p/s sau
a)\(\dfrac{1}{2};\dfrac{1}{3};\dfrac{2}{3}\) e) \(\dfrac{16}{9};\dfrac{24}{13}\)
b\(\dfrac{4}{9};-\dfrac{1}{2};\dfrac{3}{7}\) g)\(\dfrac{-2525}{2929};\dfrac{-217}{245}\)
c)\(\dfrac{3}{124};\dfrac{1}{41};\dfrac{5}{207};\dfrac{2}{83}\) h)\(\dfrac{27}{82};\dfrac{26}{75}\)
d)\(\dfrac{134}{43};\dfrac{55}{21};\dfrac{74}{19};\dfrac{116}{37}\) i)\(\dfrac{-49}{78};\dfrac{64}{-95}\)
bạn nào hard work thì làm hết hộ mk còn ko thì chỉ cần làm vài phần mai mk phải đi học mong các bạn làm giúp
tính
a) \(\dfrac{1}{5}:\dfrac{-7}{15}-\dfrac{-2}{7}\)
b) \(\dfrac{5}{6}-\dfrac{2}{3}+\dfrac{1}{4}\)
