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\(S=-2,5+\frac{23}{4}-\left(-3,25+\frac{1}{2}+\frac{13}{2}\right)\)
\(S=-\frac{5}{2}+\frac{23}{4}-\left(-\frac{13}{4}+\frac{1}{2}+\frac{13}{2}\right)\)
\(S=-\frac{5}{2}+\frac{23}{4}-\left(\frac{15}{4}\right)\)
\(S=-\frac{1}{2}\)
\(S=-2,5+\frac{23}{4}-\left(-3,25+\frac{1}{2}+\frac{13}{2}\right)\)
\(S=-2,5+\frac{23}{4}+3,25-\frac{1}{2}-\frac{13}{2}\)
\(S=\frac{23}{4}-2,5+3,25-7\)
\(S=3,25+3,25-7\)
\(S=6,5-7\)
\(S=-0,5\)
a)\(23\frac{1}{4}\cdot\frac{7}{5}+13\frac{1}{4}\)/\(\frac{-5}{7}\)
=\(23\frac{1}{4}\cdot\frac{7}{5}+13\frac{1}{4}\cdot\frac{-7}{5}\)
=\(23\frac{1}{4}\cdot\frac{7}{5}+\left(-13\frac{1}{4}\right)\cdot\frac{7}{5}\)
=\(\frac{7}{5}\cdot\left(23\frac{1}{4}-13\frac{1}{4}\right)\)
=\(\frac{7}{5}\cdot\left(23-13+\frac{1}{4}-\frac{1}{4}\right)\)
=\(\frac{7}{5}\cdot10\)
=\(14\)
b)\(\left(-3\right)^2\cdot\left(\frac{3}{4}-0.25\right)-\left(3\frac{1}{2}-1\frac{1}{2}\right)\)
=\(9\cdot\left(\frac{3}{4}-\frac{1}{4}\right)-\left(3-1+\frac{1}{2}-\frac{1}{2}\right)\)
=\(9\cdot\frac{1}{2}-2\)
=\(\frac{9}{2}-2\)
=\(\frac{9}{2}-\frac{4}{2}\)
=\(\frac{5}{2}\)
Nếu mình còn sai hay thiếu chỗ nào thì ae bảo mình nha :))
e) \(\frac{1}{7}.\frac{-3}{8}+\frac{-13}{8}.\frac{1}{7}\)
\(=\frac{1}{7}.\left[\left(-\frac{3}{8}\right)+\left(-\frac{13}{8}\right)\right]\)
\(=\frac{1}{7}.\left(-2\right)\)
\(=-\frac{2}{7}.\)
Chúc bạn học tốt!
Lời giải:
a) $2^3.3^2=8.9=72$
b) $1\frac{4}{5}+\frac{6}{29}-\frac{4}{5}+\frac{23}{29}$
$=1+\frac{4}{5}+\frac{6}{29}-\frac{4}{5}+\frac{23}{29}$
$=1+(\frac{4}{5}-\frac{4}{5})+(\frac{6}{29}+\frac{23}{29})$
$=1+0+\frac{29}{29}=1+0+1=2$
c)
$\frac{-4}{13}.\frac{5}{17}+\frac{-12}{13}.\frac{4}{17}+\frac{4}{13}$
$=\frac{-4}{13}.\frac{5}{17}+\frac{-4}{13}.\frac{12}{17}+\frac{-4}{13}.(-1)$
$=\frac{-4}{13}(\frac{5}{17}+\frac{12}{17}-1)$
$=\frac{-4}{13}.(\frac{17}{17}-1)=\frac{-4}{13}.0=0$
\(S=2,5+\frac{23}{4}-\left(-3,75+\frac{1}{2}+\frac{13}{2}\right)\)
\(S=\frac{-25}{10}+\frac{23}{4}+3,75+\frac{1}{2}+\frac{13}{2}\)
\(S=\frac{-5}{2}+\frac{23}{4}+\frac{-375}{100}+\frac{1}{2}+\frac{13}{2}\)
\(S=\frac{-5}{2}+\frac{23}{4}+\frac{-15}{4}+\frac{1}{2}+\frac{13}{2}\)
\(S=\frac{-10}{4}+\frac{23}{4}+\frac{-15}{4}+\frac{2}{4}+\frac{26}{4}\)
\(S=\frac{26}{4}=\frac{13}{2}\)
cảm ơn nhiều nhiều nhiều nha
