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c) x=-2 nha
d) =\(\frac{1}{5.6}\)+\(\frac{1}{6.7}\)+......+\(\frac{1}{11.12}\)
=\(\frac{1}{5}\)-\(\frac{1}{6}\)+\(\frac{1}{6}\)-\(\frac{1}{7}\)+.....+\(\frac{1}{11}\)-\(\frac{1}{12}\)
=\(\frac{1}{5}\)-\(\frac{1}{12}\)= \(\frac{7}{60}\)
1) \(\left(\frac{7}{8}-\frac{3}{4}\right).1\frac{1}{3}-\frac{2}{7}.\left(3,5\right)^2\)
= \(\frac{1}{8}.\frac{4}{3}-\frac{2}{7}.\frac{49}{4}\) = \(\frac{-10}{3}\)
2) \(\frac{5}{4}:\frac{1}{2}-\frac{3}{4}\) = \(\frac{7}{4}\)
\(\frac{6}{7}+\frac{5}{8}\div5-\frac{3}{16}.\left(-2\right)^2\)
\(=\frac{6}{7}+\frac{1}{8}-\frac{3}{16}.4\)
\(=\frac{48}{56}+\frac{7}{56}-\frac{3}{4}\)
\(=\frac{55}{56}-\frac{42}{56}\)
\(=\frac{13}{56}\)
\(\frac{2}{3}+\frac{1}{3}\left(-\frac{4}{9}+\frac{5}{6}\right)\div\frac{7}{12}\)
\(=\frac{2}{3}+\frac{1}{3}.\frac{7}{18}.\frac{12}{7}\)
\(=\frac{2}{3}+\frac{12}{54}\)
\(=\frac{6}{9}+\frac{2}{9}\)
\(=\frac{8}{9}\)
a) ( \(\frac{3}{8}\)+\(\frac{-1}{4}\)+\(\frac{5}{12}\)): \(\frac{2}{3}\)
=(\(\frac{9}{24}\)+\(\frac{-6}{24}\)+\(\frac{10}{24}\)):\(\frac{2}{3}\)
=\(\frac{13}{24}\):\(\frac{2}{3}\)
=\(\frac{13}{16}\)
Câu b) bn tự làm nha , mik đg có việc bận r ....Chúc bn làm tốt
\(A=-7+\frac{3}{4}-\frac{1}{3}-6+\frac{5}{4}-\frac{4}{3}-3-\frac{7}{4}+\frac{5}{3}\)
\(A=\left(-7-6-3\right)+\left(\frac{3}{4}+\frac{5}{4}-\frac{7}{4}\right)+\left(\frac{5}{3}-\frac{1}{3}-\frac{4}{3}\right)\)
\(A=-16+\frac{1}{4}+0\)
\(A=-15\frac{3}{4}\)
\(A=\left(-7+\frac{3}{4}-\frac{1}{3}\right)-\left(6-\frac{5}{4}+\frac{4}{3}\right)-\left(3+\frac{7}{4}-\frac{5}{3}\right)\)
\(=-7+\frac{3}{4}-\frac{1}{3}-6+\frac{5}{4}-\frac{4}{3}-3-\frac{7}{4}+\frac{5}{3}\)
\(=\left(-7-6-3\right)+\left(\frac{3}{4}+\frac{5}{4}-\frac{7}{4}\right)+\left(\frac{-1}{3}-\frac{4}{3}+\frac{5}{3}\right)\)
\(=-16-\frac{1}{4}\)
\(A=\frac{1}{4}:\left(10,3-9,8\right)-\frac{3}{4}\)
\(A=\frac{1}{4}:\left(0,5\right)-\frac{3}{4}\)
\(A=\frac{1}{4}:\frac{1}{2}-\frac{3}{4}\)
\(A=\frac{1}{4}\cdot2-\frac{3}{4}=\frac{1}{2}-\frac{3}{4}=\frac{2}{4}-\frac{3}{4}=\frac{-1}{4}\)
Bài 1:
a, \(A=\frac{1}{4}:0,5-\frac{3}{4}\)
\(=\frac{1}{2}-\frac{3}{4}\)
\(=\frac{-1}{4}\)
b, \(B=\frac{6}{7}+\frac{5}{8}:5-\frac{3}{16}.\left(-2\right)^2\)
\(=\frac{6}{7}+\frac{1}{8}-\frac{3}{4}\)
\(=\frac{6}{7}+\frac{-5}{8}\)
\(=\frac{13}{56}\)
Hk tốt