\(\frac{15}{24}\)va \(\frac{18}{16}\)
đề bài:quy đồng mẫu số
a)
\(\frac{14}{15};\frac{47}{45}va\frac{5}{4}?\)
b)
\(\frac{7}{12};\frac{11}{18}va\frac{25}{24}?\)
đề bài ;quy đồng mẫu số
a)
\(\frac{14}{15};\frac{47}{45}va\frac{5}{4}?\)
b)
\(\frac{7}{12};\frac{11}{18}va\frac{25}{24}?\)
Bn tìm ra Mẫu số Chung là sẽ bt đc
Cách đơn giản là bn bấm máy tính
=)))
a) Ta có: 15 = 3 . 5; 45 = 3^2 . 5; 4 = 2^2
=> MC = 2^2 . 3^2 . 5 = 4 . 9 . 5 = 36 . 5 = 180
14/15 = 14 . 12/ 15 . 12 = 168/180
47/45 = 47 . 4/ 45 . 4 = 188/180
5/4 = 5 . 45/4 . 45 = 225/180
Vậy quy đồng mẫu số các phân số 14/15; 47/45 và 5/4 ta được 168/180; 188/180 và 225/180
b) Ta có: 12 = 2^2 . 3; 18 = 2 . 3^2; 24 = 2^3 . 3
=> MC = 2^3 . 3^2 = 8 . 9 = 72
7/12 = 7 . 6/12 . 6 = 42/72
11/18 = 11 . 4/18 . 4 = 44/72
25/24 = 25 . 3/24 . 3 = 75/72
Vậy quy đồng mẫu số các phân số 7/12; 11/18 và 25/24 ta được 42/72; 44/72 và 75/72
Bài 1:
a, \(\frac{2}{5}.\frac{1}{3}-\frac{2}{15}:\frac{1}{5} +\frac{3}{5}.\frac{1}{3}\)
b, \(\frac{9}{27}+\frac{8}{24}+\frac{18}{27}-\frac{-16}{24}+\frac{2}{3}\)
c,\(\left(4-\frac{5}{12}\right):2+\frac{5}{24}\)
a) -1/3
b)8/3
c)2
k cho mk nha mk cảm ơn nhiều
\(a.\frac{27.45+27.55}{2+4+6+...+14+16+18}\)
\(b.\frac{26.108-26.12}{32-28+24-20+16-12+8-4}\)
\(c.\frac{27.4500+135.550.2}{2+4+6+...+14+16+18}\)
\(d.\frac{48.700-24.45.20}{45-40+35-30+25-20+15-10+5}\)
\(a.\frac{27.45+27.55}{2+4+6+...+14+16+18}=\frac{27.100}{\frac{\left(2+18\right).9}{2}}=30\)
\(b.\frac{26.108-26.12}{32-28+24-20+16-12+8-4}=\frac{26\left(108-12\right)}{\left(32-28\right).4}=\frac{26.96}{4.4}=156\)
\(c.\frac{27.4500+135.550.2}{2+4+6+...+14+16+18}=\frac{270.450+270.550}{\frac{\left(2+8\right).9}{2}}\)
\(d.\frac{48.700-24.45.20}{45-40+35-30+25-20+15-10+5}=\frac{48.700-48.450}{5.5}\)\(=\frac{48\left(700-450\right)}{25}=\frac{48.250}{25}=480\)
#ĐinhBa
\(\frac{9}{27}+\frac{8}{24}+\frac{18}{27}-\frac{-16}{24}+\frac{2}{3}\)
\(\frac{9}{27}+\frac{8}{24}+\frac{18}{27}+\frac{16}{24}+\frac{2}{3}\)
=\(\frac{1}{3}+\frac{1}{3}+\frac{2}{3}+\frac{2}{3}+\frac{2}{3}\)
\(=\frac{8}{3}\)
\(\frac{9}{27}+\frac{8}{24}+\frac{18}{27}-\frac{-16}{24}+\frac{2}{3}\)
\(=\frac{9}{27}+\frac{8}{24}+\frac{18}{27}+\frac{16}{24}+\frac{2}{3}\)
\(=\frac{1}{3}+\frac{1}{3}+\frac{2}{3}+\frac{2}{3}+\frac{2}{3}\)
\(=\left[\frac{1}{3}+\frac{2}{3}\right]+\left[\frac{1}{3}+\frac{2}{3}\right]+\frac{2}{3}\)
\(=1+1+\frac{2}{3}=2+\frac{2}{3}=\frac{8}{3}\)
\(\frac{9}{27}+\frac{8}{24}+\frac{18}{27}-\frac{-16}{24}+\frac{2}{3}\)
\(\frac{1}{3}+\frac{1}{3}+\frac{2}{3}+\frac{2}{3}+\frac{2}{3}\)
\(\frac{2}{3}+\frac{2}{3}+\frac{2}{3}+\frac{2}{3}\)
\(\frac{8}{3}\)
\(\frac{9+\frac{9}{11}+\frac{18}{23}-\frac{27}{37}}{8+\frac{8}{11}+\frac{16}{23}-\frac{24}{37}}-\frac{2+\frac{16}{29}-\frac{24}{13}-\frac{32}{11}}{3+\frac{24}{29}-\frac{36}{13}-\frac{48}{11}}\)
Thuc hien phep tinh
Đặt \(A=\frac{9+\frac{9}{11}+\frac{18}{23}-\frac{27}{37}}{8+\frac{8}{11}+\frac{16}{23}-\frac{24}{37}}-\frac{2+\frac{16}{29}-\frac{24}{13}-\frac{32}{11}}{3+\frac{24}{29}-\frac{36}{13}-\frac{48}{11}}\)\(=\frac{9\left(1+\frac{1}{11}+\frac{2}{23}-\frac{3}{37}\right)}{8\left(1+\frac{1}{11}+\frac{2}{23}-\frac{3}{37}\right)}-\frac{2\left(1+\frac{8}{29}-\frac{12}{13}-\frac{16}{11}\right)}{3\left(1+\frac{8}{29}-\frac{12}{13}-\frac{16}{11}\right)}\)
\(=\frac{9}{8}-\frac{2}{3}\)(do \(1+\frac{1}{11}+\frac{2}{23}-\frac{3}{37};1+\frac{8}{29}-\frac{12}{13}-\frac{16}{11}\ne0\))
\(=\frac{27}{24}-\frac{16}{24}=\frac{11}{24}.\)
Vậy A = \(\frac{11}{24}.\)
Bài 1 :Rút gọn rồi so sánh phân số:
\(\frac{18}{24}\)và \(\frac{15}{25}\)
Bài 2: So sánh phân số bằng cách hợp lí:
a) \(\frac{24}{32}\)vừa \(\frac{9}{21}\) \(\frac{15}{25}va\frac{12}{15}\) b) \(\frac{5}{6}va\frac{6}{5}\) \(\frac{7}{5}va\frac{5}{3}\)
\(\frac{18}{24}=\frac{18:6}{24:6}=\frac{3}{4}\)
\(\frac{15}{25}=\frac{15:5}{25:5}=\frac{3}{5}\)
\(\frac{3}{4}>\frac{3}{5}\) vì cùng bằng tử số, mẫu số của phân số nào lớn thì nhỏ hơn
2) a) \(\frac{24}{32}=\frac{3}{4}\)
\(\frac{9}{21}=\frac{3}{7}\) \(\Rightarrow\frac{3}{4}>\frac{3}{7}\) ( giải thích tương tự như trên)
những câu sau tương tự
Bài 1
\(\frac{18}{24}=\frac{18:6}{24:6}=\frac{3}{4}\)
\(\frac{15}{25}=\frac{15:5}{25:5}=\frac{3}{5}\)
Vì 4 < 5 => \(\frac{3}{4}>\frac{3}{5}\)( Cùng tử, mẫu số nào nhỏ hơn thì p.s đó lớn hơn )
=> \(\frac{18}{24}>\frac{15}{25}\)
Bài 2.
a) \(\frac{24}{32}\)và \(\frac{9}{21}\)
\(\frac{24}{32}=\frac{24:8}{32:8}=\frac{3}{4}\); \(\frac{9}{21}=\frac{9:3}{21:3}=\frac{3}{7}\)
Vì 4 < 7 => \(\frac{3}{4}>\frac{3}{7}\)=> \(\frac{24}{32}>\frac{9}{21}\)
\(\frac{15}{25}\)và \(\frac{12}{15}\)
\(\frac{15}{25}=\frac{15:5}{25:5}=\frac{3}{5}\); \(\frac{12}{15}=\frac{12:3}{15:3}=\frac{4}{5}\)
Vì 3 < 4 => \(\frac{3}{5}< \frac{4}{5}\)=> \(\frac{15}{25}< \frac{12}{15}\)
b) \(\frac{5}{6}\)và \(\frac{6}{5}\)
Ta có : \(\frac{5}{6}< 1< \frac{6}{5}\)
=> \(\frac{5}{6}< \frac{6}{5}\)
\(\frac{7}{5}\)và \(\frac{5}{3}\)
Quy đồng mẫu số ta được : \(\frac{7}{5}=\frac{7\cdot3}{5\cdot3}=\frac{21}{15}\); \(\frac{5}{3}=\frac{5\cdot5}{3\cdot5}=\frac{25}{15}\)
Vì 21 < 25 => \(\frac{21}{15}< \frac{25}{15}\)=> \(\frac{7}{5}< \frac{5}{3}\)
Rut gon: \(A=\frac{9+\frac{9}{11}+\frac{18}{23}-\frac{27}{27}}{8+\frac{8}{11}+\frac{16}{23}-\frac{24}{37}}-\frac{2+\frac{16}{29}-\frac{24}{13}-\frac{32}{11}}{3+\frac{24}{29}-\frac{36}{13}-\frac{48}{11}}\)
Tính :
a)\(\frac{-6}{35}.\frac{-49}{60}\)
b) \(\frac{-16}{25}.\frac{-5}{24}\)
c) \(\frac{15}{-17}.\frac{5}{18}\)
a) \(\frac{-6}{35}.\frac{-49}{60}=\frac{\left(-6\right).\left(-49\right)}{35.60}=\frac{\left(-6\right).\left(-7\right).\left(-7\right)}{\left(-5\right).\left(-7\right).\left(-6\right).\left(-10\right)}=\frac{-7}{\left(-5\right).\left(-10\right)}=\frac{-7}{50}\)
b) \(\frac{-16}{25}.\frac{-5}{24}=\frac{\left(-16\right).\left(-5\right)}{25.24}=\frac{\left(-8\right).2.\left(-5\right)}{\left(-5\right).\left(-5\right).\left(-8\right).\left(-3\right)}=\frac{2}{\left(-5\right).\left(-3\right)}=\frac{2}{15}\)
c) \(\frac{15}{-17}.\frac{5}{18}=\frac{15.5}{\left(-17\right).18}=\frac{5.3.5}{\left(-17\right).3.6}=\frac{5.5}{\left(-17\right).6}=\frac{25}{-102}\)
a) \(\frac{-6}{35}\cdot\frac{-49}{60}\)
\(=\frac{\left(-6\right)\cdot\left(-49\right)}{35\cdot60}\)
\(=\frac{294}{2100}=\frac{7}{50}\)
b)\(\frac{-16}{25}\cdot\frac{-5}{24}\)
\(=\frac{\left(-16\right)\cdot\left(-5\right)}{25\cdot24}\)
\(=\frac{80}{600}=\frac{2}{15}\)
c)\(\frac{15}{-17}\cdot\frac{5}{18}\)
\(=\frac{15\cdot5}{\left(-17\right)\cdot18}\)
\(=\frac{75}{-306}=\frac{25}{-102}\)
a, = 7/50
b, = 2/15
c, = -25/102
Tk mk nha