\(\dfrac{21}{x}\times3=\dfrac{7}{3}\)
\(\dfrac{21}{x}=\dfrac{7}{3}:3\)
\(\dfrac{21}{x}=\dfrac{7}{3}\times\dfrac{1}{3}\)
\(\dfrac{21}{x}=\dfrac{7}{9}\)
\(21:x=\dfrac{7}{9}\)
\(x=21:\dfrac{7}{9}\)
\(x=27\)
Vậy Chọn C
Bài 2: Tính nhanh:
a) \(\dfrac{3}{4}\cdot\dfrac{8}{9}\cdot\dfrac{15}{16}\cdot\dfrac{24}{25}\cdot.....\cdot\dfrac{120}{121}\cdot\dfrac{143}{144}\)
b)\(\dfrac{5}{9}\cdot\dfrac{21}{25}\cdot\dfrac{45}{49}\cdot\dfrac{77}{81}\cdot.....\dfrac{357}{361}\cdot\dfrac{437}{441}\)
ai làm đúng mk dùng 3nick mk tick cho :))))
bài 2: kết quả phép tính \(\dfrac{7}{19}\) x \(\dfrac{1}{3}\) + \(\dfrac{7}{19}\) x \(\dfrac{2}{3}\)=
a. \(\dfrac{14}{21}\)
b.\(\dfrac{21}{19}\)
c.\(\dfrac{14}{57}\)
d.\(\dfrac{7}{19}\)
tìm x
a) \(1\dfrac{1}{2}:x=\dfrac{1}{2}\) b)\(\dfrac{7}{9}-x=\dfrac{2}{3}\) c)\(\dfrac{8}{7}:x=\dfrac{6}{7}\) d)\(\dfrac{9}{5}-x=\dfrac{3}{7}\)
a)\(\dfrac{7}{8}\)x\(\dfrac{3}{13}\)+\(\dfrac{4}{9}\)x\(\dfrac{4}{13}\)
b)\(\dfrac{6}{5}\)+\(\dfrac{7}{3}\)+\(\dfrac{8}{9}\)
c)23: \(\dfrac{5}{14}\)+\(\dfrac{6}{7}\)+\(\dfrac{4}{9}\)
d)\(4\dfrac{1}{4}\)+\(7\dfrac{3}{7}\)-\(2\dfrac{4}{17}\)
e)8-(9\(\dfrac{2}{11}\)+\(\dfrac{8}{33}\))
So sánh các phân số:
a,\(\dfrac{1}{5}và\dfrac{3}{5}\) b\(\dfrac{8}{21}và\dfrac{8}{9}\) c,\(\dfrac{3}{5}và1\) d,\(\dfrac{7}{5}và1\)
1. Giá trị của x trong : x : \(\dfrac{2}{9}\) = 18 là:
a) 2 b) \(\dfrac{162}{2}\) c) 4 d) \(\dfrac{18}{9}\)
2. \(\dfrac{3}{5}\) của 4 tấn là:
a) 2400kg b) 240kg c) 24kg d) 24 000kg
3. 25ha = ........km2
a) 0,0025 b) 0,025 c) 0,25 d) 2,5
a) \(\dfrac{3}{7}\)+\(\dfrac{4}{9}\)+\(\dfrac{8}{14}\)+\(\dfrac{10}{18}\)
b) \(\dfrac{1}{2}\)x\(\dfrac{2}{3}\):\(\dfrac{5}{6}\)x\(\dfrac{5}{6}\)
bài này là bài tính bằng cách thuận tiện nhất nha !
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,\(\dfrac{7}{2}-\dfrac{3}{10}:\dfrac{2}{5}\)
Tính thuận tiện :
M = 3 + \(\dfrac{4}{9}\) x \(\dfrac{7}{25}\) x \(\dfrac{27}{12}\) x \(3\dfrac{4}{7}\) - \(\dfrac{7}{25}\)
Giải giúp e với
