1, Thực hiện phép tính bằng cách tính hợp lí
A)(9/25-2x18):(3 4/5+0,2)
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(\(\dfrac{9}{25}\) - 2.18) : (\(\dfrac{19}{5}\) + 0,2)
=(\(\dfrac{9}{25}\) - 2.18) : (\(\dfrac{19}{5}\) +\(\dfrac{1}{5}\) )
=(\(\dfrac{9}{25}\)- 36) : 4
=\(\dfrac{-117}{5}\) : 4
= \(\dfrac{-117}{20}\)
(\(\dfrac{9}{25}\)-2.18) : (\(\dfrac{19}{5}\) +0,2)
= (\(\dfrac{9}{25}\)- 2.18) : (\(\dfrac{19}{5}\)+\(\dfrac{1}{5}\))
= (\(\dfrac{9}{25}\)-36): 4
= \(\dfrac{-891}{25}\):4
=\(\dfrac{-891}{100}\)
a)\(=12\times3+4\times12+12\times3=12\times\left(3+4+3\right)=12\times10=120\)
b)\(=25\times7-25\times2-3\times25-2\times25=25\times\left(7-2-3-2\right)=0\)
2:
a: \(=\dfrac{1}{3}\left(-\dfrac{4}{5}-\dfrac{6}{5}\right)=-\dfrac{1}{3}\cdot2=-\dfrac{2}{3}\)
1:
\(A=7-\dfrac{3}{4}+\dfrac{1}{3}-6-\dfrac{5}{4}+\dfrac{4}{3}-5+\dfrac{7}{4}-\dfrac{5}{3}\)
\(=-4-\dfrac{1}{4}=-\dfrac{17}{4}\)
Bài 1:
\(A=\left(7-\dfrac{3}{4}+\dfrac{1}{3}\right)-\left(6+\dfrac{5}{4}-\dfrac{4}{3}\right)-\left(5-\dfrac{7}{4}+\dfrac{5}{3}\right)\)
\(A=7-\dfrac{3}{4}+\dfrac{1}{3}-6-\dfrac{5}{4}+\dfrac{4}{3}-5+\dfrac{7}{4}-\dfrac{5}{3}\)
\(A=\left(7-6-5\right)-\left(\dfrac{3}{4}+\dfrac{5}{4}-\dfrac{7}{4}\right)+\left(\dfrac{1}{3}+\dfrac{4}{3}-\dfrac{5}{3}\right)\)
\(A=-4-\dfrac{3+5-7}{4}+\dfrac{1+4-5}{3}\)
\(A=-4-\dfrac{1}{4}+\dfrac{0}{3}\)
\(A=-\dfrac{16}{4}-\dfrac{1}{4}+0\)
\(A=\dfrac{-16-1}{4}\)
\(A=-\dfrac{17}{4}\)
Bài 2:
\(\dfrac{1}{3}\cdot-\dfrac{4}{5}+\dfrac{1}{3}\cdot-\dfrac{6}{5}\)
\(=\dfrac{1}{3}\cdot\left(-\dfrac{4}{5}-\dfrac{6}{5}\right)\)
\(=\dfrac{1}{3}\cdot\dfrac{-4-6}{5}\)
\(=\dfrac{1}{3}\cdot\dfrac{-10}{5}\)
\(=\dfrac{1}{3}\cdot-2\)
\(=-\dfrac{2}{3}\)
\(\frac{5}{3}+-\frac{2}{7}-\left(-\frac{1}{2}\right)=\frac{29}{21}-\left(-\frac{1}{2}\right)=\frac{79}{42}\)
b . tương tự
giúp tớ nhé
tớ bị trừ 590 điểm
cảm ơn trước
\((\frac{9}{25}-2.18):\left(3\frac{4}{5}-0,2\right)\)
=-1,82 : 4
=-0,455
\(\left(\frac{9}{25}-2.18\right):\left(3\frac{4}{5}-0,2\right)\)
= -1,82:4=-0,455