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b1 -10/14
b2 -4/5
b3
a 2/9-7/8.x=1/3
7/8.x=2/9-1/3=-1/9
x=-1/9:-7/8=8/63
b 23/7.x-1/8=11/4
23/7.x=11/4+1/8=23/8
x=23/8:23/7=7/8
b4
Quyển truyện cs số trang:
36:(1−1/4−9/20)=120(trang)
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: \(=\dfrac{49\cdot8}{10}=\dfrac{196}{5}\)
Bài 1:
a) \(\dfrac{-5}{6}\ne\dfrac{10}{-14}\left(\dfrac{10}{-14}=-\dfrac{5}{7}\right).\)
b) \(\dfrac{-15}{-60}\ne\dfrac{-3}{12}\left(\dfrac{-15}{-60}=\dfrac{1}{4}\right).\)
Bài 2:
a) \(\dfrac{20}{-140}=-\dfrac{1}{7}.\)
b) \(\dfrac{4.18}{9.12}=\dfrac{72}{108}=\dfrac{2}{3}.\)
c) \(\dfrac{17.25-17.3}{2.\left(-15\right)}=\dfrac{17.\left(25-3\right)}{-30}=-\dfrac{17.22}{30}=\dfrac{374}{30}=\dfrac{187}{15}.\)
Bài 3:
a) \(\dfrac{-3}{5}< \dfrac{4}{-7}.\)
b) \(\dfrac{-4}{21}>\dfrac{-7}{35}.\)
c) \(\dfrac{-7}{24}>\dfrac{-2}{3}.\)
d) \(\dfrac{-52}{167}< \dfrac{-3}{-4}.\)
a \(\dfrac{-2}{5}\)
b -1
c \(\dfrac{2}{5}\)
d \(\dfrac{-18}{11}\)
b: \(27D=3^{14}+3^{17}+...+3^{2024}\)
\(\Leftrightarrow26D=3^{2024}-3^{11}\)
hay \(D=\dfrac{3^{2024}-3^{11}}{26}\)
c: \(25E=-5^4-5^6-...-5^{1002}\)
\(\Leftrightarrow24E=-5^{1002}+5^2\)
hay \(E=\dfrac{-5^{1002}+5^2}{24}\)
1. \(\frac{9}{30}=\frac{3}{10};\frac{98}{80}=\frac{49}{40};\frac{15}{1000}=\frac{3}{200}\)
Vì \(200⋮10;200⋮40\)
=> BCNN(10; 40; 200) = 200
200 : 10 = 20
200 : 40 = 5
=> \(\frac{3}{10}=\frac{3\cdot20}{10\cdot20}=\frac{60}{200}\), \(\frac{49}{40}=\frac{49\cdot5}{40\cdot5}=\frac{245}{200}\)
a)\(\frac{484}{-860}=\frac{121}{215}\)
b)\(\frac{14.20-70.13}{21.10+7.80}=\frac{7.2.10.2-7.10.13}{7.3.10+7.8.10}=\frac{7.4.10-7.10.13}{7.3.10+7.8.10}=\frac{7.10.\left(4-13\right)}{7.10.\left(3+8\right)}=\frac{-9}{11}\)
c)\(\frac{-10.21.35}{15.\left(-14\right).\left(-4\right)}=\frac{-2.5.3.7.7.5}{3.5.7.\left(-2\right).\left(-4\right)}=\frac{35}{-4}\)
d)\(\frac{\left(-4\right)^3.27^2.\left(-10\right)^3}{8^3.\left(-9\right)^2.25^2}=\frac{\left(-2^2\right)^3.\left(3^3\right)^2.\left(-2.5\right)^3}{\left(2^3\right)^3.\left[\left(-3\right)^2\right]^2.\left(5^2\right)^2}=\frac{-2^5.3^5.\left(-2\right)^3.5^3}{2^6.\left(-3\right)^4.5^4}=\frac{2^2.3}{5}=\frac{4.3}{5}=\frac{12}{5}\)
a,\(\frac{484}{-860}=\frac{484:\left(-4\right)}{-860:\left(-4\right)}=\frac{-121}{215}\)
b,\(\frac{14.20-70.13}{21.10+7.80}\)\(=\frac{280-910}{210+560}=\frac{-630}{770}=\frac{-9}{11}\)
c,\(\frac{-10.21.35}{15.\left(-14\right).\left(-4\right)}=\frac{1.\left(-3\right).35}{3.2.2}=\frac{105}{12}=8\frac{3}{4}\)
d,tự làm