Tính (theo mẫu).
a) \(3:\dfrac{5}{7}\) b) \(4:\dfrac{1}{3}\) c) \(\dfrac{5}{7}:3\)
Tính (theo mẫu).
Mẫu: \(\dfrac{2}{3}+\dfrac{5}{3}=\dfrac{2+5}{3}=\dfrac{7}{3}\)
a) \(\dfrac{2}{7}+\dfrac{4}{7}\) b) \(\dfrac{23}{13}+\dfrac{8}{13}\) c) \(\dfrac{27}{125}+\dfrac{16}{125}\)
a) \(\dfrac{2}{7}+\dfrac{4}{7}=\dfrac{2+4}{7}=\dfrac{6}{7}\)
b) \(\dfrac{23}{13}+\dfrac{8}{13}=\dfrac{23+8}{13}=\dfrac{31}{13}\)
c) \(\dfrac{27}{125}+\dfrac{16}{125}=\dfrac{27+16}{125}=\dfrac{43}{125}\)
a)\(\dfrac{2}{7}\) + \(\dfrac{4}{7}\) = \(\dfrac{6}{7}\)
b)\(\dfrac{23}{13}\) + \(\dfrac{8}{13}\) = \(\dfrac{31}{13}\)
c)\(\dfrac{27}{125}\) + \(\dfrac{16}{125}\) = \(\dfrac{43}{125}\)
Tính rồi rút gọn (theo mẫu):
Mẫu: \(\dfrac{5}{6}+\dfrac{4}{6}=\dfrac{5+4}{6}=\dfrac{9}{6}=\dfrac{3}{2}\) |
a) \(\dfrac{1}{8}+\dfrac{5}{8}\) b) \(\dfrac{1}{15}+\dfrac{4}{15}\) c) \(\dfrac{5}{9}+\dfrac{7}{9}\) d) \(\dfrac{23}{100}+\dfrac{27}{100}\)
a: \(\dfrac{1}{8}+\dfrac{5}{8}=\dfrac{1+5}{8}=\dfrac{6}{8}=\dfrac{3}{4}\)
b: \(\dfrac{1}{15}+\dfrac{4}{15}=\dfrac{1+4}{15}=\dfrac{5}{15}=\dfrac{1}{3}\)
c: \(\dfrac{5}{9}+\dfrac{7}{9}=\dfrac{5+7}{9}=\dfrac{12}{9}=\dfrac{4}{3}\)
d: \(\dfrac{23}{100}+\dfrac{27}{100}=\dfrac{23+27}{100}=\dfrac{50}{100}=\dfrac{1}{2}\)
Tính (theo mẫu):
a)
\(5+\dfrac{3}{2}\) \(\dfrac{3}{4}+2\) \(\dfrac{8}{9}+3\)
b)
\(1-\dfrac{1}{2}\) \(5-\dfrac{7}{3}\) \(\dfrac{11}{2}-3\)
a: \(5+\dfrac{3}{2}=\dfrac{10}{2}+\dfrac{3}{2}=\dfrac{10+3}{2}=\dfrac{13}{2}\)
\(\dfrac{3}{4}+2=\dfrac{3}{4}+\dfrac{8}{4}=\dfrac{3+8}{4}=\dfrac{11}{4}\)
\(\dfrac{8}{9}+3=\dfrac{8}{9}+\dfrac{27}{9}=\dfrac{8+27}{9}=\dfrac{35}{9}\)
b: \(1-\dfrac{1}{2}=\dfrac{2}{2}-\dfrac{1}{2}=\dfrac{2-1}{2}=\dfrac{1}{2}\)
\(5-\dfrac{7}{3}=\dfrac{15}{3}-\dfrac{7}{3}=\dfrac{15-7}{3}=\dfrac{8}{3}\)
\(\dfrac{11}{2}-3=\dfrac{11}{2}-\dfrac{6}{2}=\dfrac{11-6}{2}=\dfrac{5}{2}\)
Tìm phân số thích hợp (theo mẫu).
Mẫu: \(\dfrac{3}{5}\times?=\dfrac{4}{7}\) \(\dfrac{4}{7}:\dfrac{3}{5}=\dfrac{20}{21}\) |
a) \(\dfrac{2}{5}\times?=\dfrac{3}{10}\) b) \(\dfrac{1}{8}:?=\dfrac{1}{5}\)
a) \(\dfrac{2}{5}\times?=\dfrac{3}{10}\)
\(?=\dfrac{3}{10}:\dfrac{2}{5}=\dfrac{3}{4}\)
b) \(\dfrac{1}{8}:?=\dfrac{1}{5}\)
\(?=\dfrac{1}{8}:\dfrac{1}{5}=\dfrac{5}{8}\)
a: Phân số cần tìm là: \(\dfrac{3}{10}:\dfrac{2}{5}=\dfrac{3}{10}\cdot\dfrac{5}{2}=\dfrac{15}{20}=\dfrac{3}{4}\)
b: Phân số cần tìm là \(\dfrac{1}{8}:\dfrac{1}{5}=\dfrac{5}{8}\)
Rút gọn rồi tính (theo mẫu).
Mẫu: \(\dfrac{5}{15}+\dfrac{4}{3}=\dfrac{1}{3}+\dfrac{4}{3}=\dfrac{1+4}{3}=\dfrac{5}{3}\) |
a) \(\dfrac{21}{15}+\dfrac{2}{5}\) b) \(\dfrac{6}{16}+\dfrac{1}{8}\) c) \(\dfrac{3}{12}+\dfrac{3}{4}\)
a) \(\dfrac{21}{15}\) + \(\dfrac{2}{5}\) = \(\dfrac{9}{5}\)
b) \(\dfrac{6}{16}\) + \(\dfrac{1}{8}\) = \(\dfrac{1}{2}\)
c) \(\dfrac{3}{12}\) + \(\dfrac{3}{4}\) = 1
Tính (theo mẫu):
a) \(\dfrac{1}{4}\) của 20 km. b) \(\dfrac{1}{7}\) của 28 g.
c) \(\dfrac{3}{10}\) của 100 ml. d) \(\dfrac{3}{4}\) của 640 tấn.
e) \(\dfrac{5}{8}\) của 40 m2. g) \(\dfrac{2}{3}\) của 1 giờ.
a) Ta có \(\dfrac{1}{4}\) của 20 km là:
\(20\times\dfrac{1}{4}=5\left(km\right)\)
Vậy: ...
b) Ta có: \(\dfrac{1}{7}\) của 28 g là:
\(\dfrac{1}{7}\times28=4\left(g\right)\)
Vậy: ....
c) Ta có \(\dfrac{3}{10}\) của 100 ml là:
\(\dfrac{3}{10}\times100=30\left(ml\right)\)
Vậy: ...
d) Ta có \(\dfrac{3}{4}\) của 640 tấn là:
\(\dfrac{3}{4}\times640=480\) (tấn)
Vậy: ...
e) Ta có \(\dfrac{5}{8}\) của \(40m^2\) là:
\(\dfrac{5}{8}\times40=25\left(m^2\right)\)
Vậy: ...
g) Đổi: 1 giờ = 60 phút
Ta có \(\dfrac{2}{3}\) của 1 giờ là:
\(\dfrac{2}{3}\times60=40\) (phút)
Vậy: ...
a) Ta có 1/4 của 20 là: 20 × 1/4 = 5
Vậy 1/4 của 20 km là 5 km
b) Ta có 1/7 của 28 là: 28 × 1/7 = 4
Vậy 1/7 của 28 g là 4 g
c) Ta có 3/10 của 100 là: 100 × 3/10 = 30
Vậy 3/10 của 100 ml là 30 ml
d) Ta có 3/4 của 640 là: 640 × 3/4 = 480
Vậy 3/4 của 640 tấn là 480 tấn
e) Ta có 5/8 của 40 là: 40 × 5/8 = 25
Vậy 5/8 của 40 m² là 25 m²
g) Ta có 2/3 của 1 là 1 × 2/3 = 2/3
Vậy 2/3 của 1 giờ là 2/3 giờ
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,\(\dfrac{7}{2}-\dfrac{3}{10}:\dfrac{2}{5}\)
\(a,5x\dfrac{7}{3}=\dfrac{5}{1}x\dfrac{7}{3}=\dfrac{35}{3};b,\dfrac{13}{4}:7=\dfrac{13}{4} :\dfrac{7}{1}=\dfrac{13}{4}x\dfrac{1}{7}=\dfrac{13}{28}\)
\(\dfrac{3}{7}+\dfrac{2}{5}+\dfrac{3}{4}=\dfrac{60}{140}+\dfrac{56}{140}+\dfrac{105}{140}=\dfrac{221}{140}\)
\(\dfrac{9}{7}-\dfrac{5}{11}x\dfrac{11}{7}=\dfrac{9}{7}-\dfrac{5}{7}=\dfrac{4}{7}\)
Tính (theo mẫu).
Mẫu: \(2+\dfrac{1}{6}=\dfrac{12}{6}+\dfrac{1}{6}=\dfrac{13}{6};1-\dfrac{1}{4}=\dfrac{4}{4}-\dfrac{1}{4}=\dfrac{3}{4}\) |
a) \(1+\dfrac{4}{9}\) b) \(5+\dfrac{1}{2}\) c) \(3-\dfrac{5}{6}\) d) \(\dfrac{31}{7}-2\)
a) \(1+\dfrac{4}{9}=\dfrac{9}{9}+\dfrac{4}{9}=\dfrac{9+4}{9}=\dfrac{13}{9}\)
b) \(5+\dfrac{1}{2}=\dfrac{10}{2}+\dfrac{1}{2}=\dfrac{10+1}{2}=\dfrac{11}{2}\)
c) \(3-\dfrac{5}{6}=\dfrac{18}{6}-\dfrac{5}{6}=\dfrac{18-5}{6}=\dfrac{13}{6}\)
d) \(\dfrac{31}{7}-2=\dfrac{31}{7}-\dfrac{14}{7}=\dfrac{31-14}{7}=\dfrac{17}{7}\)
Tính (theo mẫu).
Mẫu: \(\dfrac{1}{2}-\dfrac{5}{12}=\dfrac{6}{12}-\dfrac{5}{12}=\dfrac{6-5}{12}=\dfrac{1}{12}\) |
a) \(\dfrac{3}{4}-\dfrac{1}{8}\) b) \(\dfrac{2}{6}-\dfrac{5}{18}\) c) \(\dfrac{2}{5}-\dfrac{3}{20}\)
a) \(\dfrac{3}{4}-\dfrac{1}{8}=\dfrac{6}{8}-\dfrac{1}{8}=\dfrac{6-1}{8}=\dfrac{5}{8}\)
b) \(\dfrac{2}{6}-\dfrac{5}{18}=\dfrac{6}{18}-\dfrac{5}{18}=\dfrac{6-5}{18}=\dfrac{1}{18}\)
c) \(\dfrac{2}{5}-\dfrac{3}{20}=\dfrac{8}{20}-\dfrac{3}{20}=\dfrac{8-3}{20}=\dfrac{5}{20}=\dfrac{1}{4}\)