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c.
\(\frac{1}{3}\times\frac{5}{7}-\frac{7}{27}\times\frac{36}{14}\)
\(=\frac{1}{3}\times\frac{5}{7}-\frac{7}{3\times9}\times\frac{4\times9}{7\times2}\)
\(=\frac{1}{3}\times\frac{5}{7}-\frac{1}{3}\times\frac{4}{6}\)
\(=\frac{1}{3}\times\left(\frac{5}{7}-\frac{4}{6}\right)\)
\(=\frac{1}{3}\times\left(\frac{30-38}{42}\right)\)
\(=\frac{1}{3}\times\frac{-8}{42}\)
\(=-\frac{4}{63}\)
Chúc bạn học tốt
a) \(\left(\frac{-3}{2}+\frac{2}{5}\right):\frac{3}{7}+\left(\frac{3}{5}+\frac{-1}{4}\right):\frac{3}{7}\)
= \(\left(\frac{-3}{2}+\frac{2}{5}+\frac{3}{5}+\frac{-1}{4}\right):\frac{3}{7}\)
= \(\frac{-3}{4}:\frac{3}{7}\)
= \(\frac{-7}{4}\)
b) \(\frac{7}{8}:\left(\frac{2}{9}-\frac{1}{18}\right)+\frac{7}{8}:\left(\frac{1}{36}-\frac{5}{12}\right)\)
\(=\frac{7}{8}:\frac{1}{6}+\frac{7}{8}:\left(\frac{-7}{18}\right)\)
\(=\frac{7}{8}.6+\frac{7}{8}.\left(\frac{-18}{7}\right)\)
\(=\frac{7}{8}.\left(6+\frac{-18}{7}\right)\)
\(=\frac{7}{8}.\frac{24}{7}\)
\(=3\)
mik ko chép lại đề, mik làm luôn:
a) x - \(\frac{31}{36}=\frac{-13}{38}\)
x = \(\frac{-13}{18}+\frac{31}{36}\)
\(x=\frac{5}{36}\)
b)\(2-x-\frac{3}{7}=\frac{9}{-21}\)
\(\frac{11}{7}-x=\frac{3}{7}\)
x = \(\frac{11}{7}-\frac{3}{7}\)
x = 8/7
c) x + 3/11 = 23/44
x = 23/44 - 3/11
x = 1/4
d) \(\frac{1}{12}-x=\frac{-11}{9}\)
x = \(\frac{1}{12}+\frac{11}{9}\)
x = 47/36
e) \(x-\frac{2}{3}=\frac{-17}{3}\)
x= -17/3 + 2/3
x = -5
f) \(x-\frac{1}{2}=\frac{11}{4}.\frac{3}{11}\)
x - 1/2 = 3/4
x = 3/4 + 1/2
x = 5/4
g) \(2x+\frac{3}{8}=\frac{-21}{32}.\frac{4}{7}\)
2x + 3/8 = -3 / 8
2x = -3/8 - 3/8
2x = -9/8
x = -9/8.1/2
x = -9/16
h) x - \(\frac{x}{3}=\frac{3}{57}.\frac{19}{12}\)
x - \(\frac{x}{3}=\frac{1}{12}\)
x = \(\frac{1}{12}+\frac{x}{3}\)
x = \(\frac{1+4x}{12}\)
=> 12x = 1+4x
12x - 4x = 1
8x = 1
x = 1/8
\(A=\frac{21.99+21}{35.201-35}=\frac{21\left(99+21\right)}{35\left(201-1\right)}=\frac{21.\left(99+1+20\right)}{35.200}=\frac{21.120}{35.200}=\frac{\left(3.7\right).\left(2.2.3.\right)10}{\left(5.7\right).\left(2.2.5\right).10}=\frac{3.3}{5.5}=\left(\frac{3}{5}\right)^2\)
\(B=\frac{\left(-2\right)^{36}.3^{17}}{3^{18}.2^{35}}=\frac{2^{36}.3^{17}}{2^{35}.3^{18}}=2^{\left(36-35\right)}.3^{17-18}=2.3^{-1}=\frac{2}{3}\)
\(C=\frac{7^{100}-7^{99}}{7^{98}-7^{97}}=\frac{7^{99}\left(7^1-7^0\right)}{7^{97}\left(7^1-7^0\right)}=7^{99-97}.\frac{\left(7-1\right)}{7-1}=7^2.1=49\)
mấy bn giải chi tiết giúp mk nhé !