rút gọn các phân số sau
a) 3.5.7/14.55
b) 2^7.3^4/3^6.2^5
c)7.9-7.4/14.11-14
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a) \(\dfrac{11\cdot8-11\cdot3}{17-6}\)
\(=\dfrac{11\cdot\left(8-3\right)}{11}=5\)
b) \(\dfrac{24-12\cdot13}{12+4\cdot9}\)
\(=\dfrac{12\cdot\left(2-13\right)}{12\left(1+3\right)}=\dfrac{-11}{4}\)
a \(\dfrac{-2}{5}\)
b -1
c \(\dfrac{2}{5}\)
d \(\dfrac{-18}{11}\)
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Bài 1:
a: =-3/7
b: =-3/5
c: =1/13
d: =-1/2
Bài 2:
a: \(=\dfrac{21\cdot11}{22\cdot9}=\dfrac{1}{2}\cdot\dfrac{7}{3}=\dfrac{7}{6}\)
b: \(=\dfrac{49\cdot8}{10}=\dfrac{196}{5}\)
a: \(=\dfrac{3^6\cdot2^{21}}{5^{18}\cdot7^9\cdot7^3}=\dfrac{3^6\cdot2^{21}}{5^{18}\cdot7^{12}}\)
b: \(=\dfrac{3^{10}\cdot3^7\cdot2^7\cdot2^2}{2^9\cdot5^9\cdot5^8}=\dfrac{3^{17}}{5^{17}}\)
a: \(A=\dfrac{2\cdot8^4\cdot27^2+44\cdot6^9}{2^7\cdot6^7+2^7\cdot40\cdot9^4}\)
\(=\dfrac{2\cdot2^{12}\cdot3^6+2^2\cdot11\cdot2^9\cdot3^9}{2^7\cdot3^7\cdot2^7+2^7\cdot2^3\cdot5\cdot3^8}\)
\(=\dfrac{2^{13}\cdot3^6+2^{11}\cdot3^9\cdot11}{2^{14}\cdot3^7+2^{10}\cdot5\cdot3^8}\)
\(=\dfrac{2^{11}\cdot3^6\left(2^2+3^3\cdot11\right)}{2^{10}\cdot3^7\left(2^4+5\cdot3\right)}\)
\(=\dfrac{2\cdot301}{3\cdot31}=\dfrac{602}{93}\)
a)\(\dfrac{5}{25}=\dfrac{1}{5}\)
\(\dfrac{75}{100}=\dfrac{3}{4}\)
\(\dfrac{64}{720}=\dfrac{4}{45}\)
\(\dfrac{16}{1000}=\dfrac{2}{125}\)
b)\(\dfrac{4}{6}=\dfrac{2}{3}\)
\(\dfrac{12}{8}=\dfrac{3}{2}\)
\(\dfrac{15}{25}=\dfrac{3}{5}\)
\(\dfrac{11}{22}=\dfrac{1}{2}\)
c)\(\dfrac{5}{10}=\dfrac{1}{2}\)
\(\dfrac{12}{36}=\dfrac{1}{3}\)
\(\dfrac{9}{72}=\dfrac{1}{8}\)
\(\dfrac{75}{300}=\dfrac{1}{4}\)
d)\(\dfrac{14}{28}=\dfrac{1}{2}\)
\(\dfrac{25}{50}=\dfrac{1}{2}\)
\(\dfrac{48}{30}=\dfrac{8}{5}\)
\(\dfrac{81}{54}=\dfrac{3}{2}\)
a: 5/25=1/5
75/100=3/4
64/720=4/45
16/1000=2/125
b: 4/6=2/3
12/8=3/2
15/25=3/5
11/22=1/2
c: 5/10=1/2
12/36=1/3
9/72=1/8
75/300=1/4
d: 14/28=1/2
25/50=1/2
48/30=8/5
81/54=3/2
d)
\(\dfrac{3^9.3^{20}.2^8}{3^{24}.243.2^6}\\ =\dfrac{3^{29}.2^6.2^2}{3^{24}.3^5.2^6}\\ =\dfrac{3^{29}.2^6.4}{3^{29}.2^6}\\ =4\)
e)
\(\dfrac{2^{15}.5^3.2^6.3^4}{8.2^{18}.81.5}\\ =\dfrac{2^{21}.5^3.3^4}{2^3.2^{18}3^4.5}\\ =\dfrac{2^{21}.5.5^2.3^4}{2^{21}.3^4.5}\\ =5^2\\ =25\)
f)
\(=\dfrac{24\left(315+561+124\right)}{\dfrac{\left(1+99\right).50}{2}-500}\\ =\dfrac{24.1000}{2500-500}\\ =12\)
\(a,\dfrac{-14.15}{21.\left(-10\right)}=\dfrac{-7.2.3.5}{7.3.\left(-2\right).5}=1\)
\(b,\dfrac{5.7-7.9}{7.2+6.7}=\dfrac{7\left(5-9\right)}{7\left(2+6\right)}=\dfrac{-4}{8}=-\dfrac{1}{2}\)
\(c,\dfrac{\left(-7\right).3+2.\left(-14\right)}{\left(-5\right).7-2.7}=\dfrac{-7.\left(3+4\right)}{7\left(-5-2\right)}\)
\(=\dfrac{\left(-7\right).7}{7.\left(-7\right)}=1\)
\(d,\dfrac{3^9.3^{20}.2^8}{3^{24}.243.2^6}=\dfrac{3^{29}.2^8}{3^{24}.3^5.2^6}=\dfrac{3^{29}.2^8}{3^{29}.2^6}=2^2=4\)
\(e,\dfrac{2^{15}.5^3.2^6.3^4}{8.2^{18}.81.5}=\dfrac{2^{21}.3^4.5^3}{2^{18}.2^3.3^4.5}=\dfrac{2^{21}.3^4.5^3}{2^{21}.3^4.5}=5^2=25\)
\(f,\dfrac{24.315+3.561.8+4.124.6}{1+3+5+...+97+99-500}\)
\(=\dfrac{24.315+24.561+24.124}{1+3+5+...+97+99-500}\)
\(=\dfrac{24\left(315+561+124\right)}{1+3+5+...+97+99-500}\)
\(=\dfrac{24.1000}{1+3+5+...+97+99-500}\) (1)
Đặt A = 1 + 3 + 5 + ... + 97 + 99
Số số hạng trong A là: (99 - 1) : 2 + 1 = 50 (số)
Tổng A bằng: (99 + 1) . 50 : 2 = 2500
Thay A = 2500 vào biểu thức (1), ta được:
\(\dfrac{24.1000}{2500-500}=\dfrac{24.1000}{2.1000}=12\)
mik cần gấp ak
a) \(\frac{3\cdot5\cdot7}{14\cdot55}=\frac{3\cdot5\cdot7}{2\cdot7\cdot11\cdot5}=\frac{3}{2\cdot11}=\frac{3}{22}\)
b) \(\frac{2^7\cdot3^4}{3^6\cdot2^5}=\frac{2^2\cdot2^5\cdot3^4}{3^2\cdot3^4\cdot2^5}=\frac{2^2}{3^2}=\frac{4}{9}\)
c) \(\frac{7\cdot9-7\cdot4}{14\cdot11-14}=\frac{7\left(9-4\right)}{14\cdot\left(11-1\right)}=\frac{7\cdot5}{14\cdot10}=\frac{7\cdot5}{2\cdot7\cdot2\cdot5}=\frac{1}{2\cdot2}=\frac{1}{4}\)