bài 1:tính tổng M=\(3\frac{1}{417}\cdot\frac{1}{762}-\frac{1}{139}\cdot4\frac{761}{76}-\frac{4}{417-762}+\frac{5}{139}\)
ai giải nhanh nhất mình tick
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\(D=\left(3+\frac{1}{417}\right).\frac{1}{762}-\frac{1}{139}\left(4+\frac{761}{762}\right)-\frac{4}{417.762}+\frac{5}{139}\)
=\(\frac{3}{762}+\frac{1}{417.762}-\frac{4}{139}-\frac{761}{139.762}-\frac{4}{417.762}+\frac{5}{139}\)
=\(\frac{3}{762}-\frac{1}{139.762}+\frac{1}{139}-\frac{761}{139.762}=\frac{3}{762}+\frac{1}{139}\left(-\frac{1}{762}+1\right)-\frac{761}{139.762}=\)
\(\frac{3}{762}+\frac{761}{139.762}-\frac{761}{139.762}=\frac{3}{762}\)
= \(\frac{3}{762}+\frac{1}{417.762}-\frac{1}{139}.\left(4+\frac{761}{762}\right)-\frac{4}{417.762}+\frac{5}{139}\)
= \(\frac{3}{762}+\left(\frac{1}{417.762}-\frac{4}{417.762}\right)-\frac{1}{139}.\left(4+1-\frac{1}{762}\right)+\frac{5}{139}\)
= \(\frac{3}{762}+\frac{-3}{417.762}-\frac{5}{139}+\frac{1}{762.139}+\frac{5}{139}\)
= \(\frac{3}{762}+\left(\frac{-1}{139.762}+\frac{1}{762.139}\right)+\left(-\frac{5}{139}+\frac{5}{139}\right)=\frac{3}{762}=\frac{1}{254}\)
\(M=\dfrac{1252\cdot1}{417\cdot762}-\dfrac{3\cdot3809}{417\cdot762}-\dfrac{4}{417\cdot762}+\dfrac{5}{139}\)
\(=\dfrac{-10164}{417\cdot762}=-\dfrac{1694}{52959}\)
mình ko bít
=0,04 nhá