Thực hiện phép tính: a,(4+1/5).19/8.(2+5/8).21/5 b,25/2.(3+2/7)-23/7.(5+1/2) 31/10/2021 Bởi Audrey Thực hiện phép tính: a,(4+1/5).19/8.(2+5/8).21/5 b,25/2.(3+2/7)-23/7.(5+1/2)
a) TH1 : (4 + $\frac{1}{5}$) . $\frac{19}{8}$ + (2 + $\frac{5}{8}$) . $\frac{21}{5}$ = 4$\frac{1}{5}$ . $\frac{19}{8}$ + 2$\frac{5}{8}$ . $\frac{21}{5}$ = $\frac{21}{5}$ . $\frac{19}{8}$ + $\frac{21}{8}$ . $\frac{21}{5}$ = $\frac{21}{5}$ . ($\frac{19}{8}$ + $\frac{21}{8}$) = $\frac{21}{5}$ . $\frac{15}{4}$ = $\frac{63}{4}$ TH2 : (4 + $\frac{1}{5}$) . $\frac{19}{8}$ – (2 + $\frac{5}{8}$) . $\frac{21}{5}$ = 4$\frac{1}{5}$ . $\frac{19}{8}$ – 2$\frac{5}{8}$ . $\frac{21}{5}$ = $\frac{21}{5}$ . $\frac{19}{8}$ – $\frac{21}{8}$ . $\frac{21}{5}$ = $\frac{21}{5}$ . ($\frac{19}{8}$ – $\frac{21}{8}$) = $\frac{21}{5}$ . $\frac{-1}{4}$ = $\frac{-21}{20}$ b) $\frac{25}{2}$ . (3 + $\frac{2}{7}$) – $\frac{23}{7}$ . (5 + $\frac{1}{2}$) = $\frac{25}{2}$ . $\frac{23}{7}$ – $\frac{23}{7}$ . $\frac{11}{2}$ = $\frac{23}{7}$ . ($\frac{25}{2}$ – $\frac{11}{2}$) = $\frac{23}{7}$ . 7 = 23. Bình luận
a) TH1 : (4 + $\frac{1}{5}$) . $\frac{19}{8}$ + (2 + $\frac{5}{8}$) . $\frac{21}{5}$
= 4$\frac{1}{5}$ . $\frac{19}{8}$ + 2$\frac{5}{8}$ . $\frac{21}{5}$
= $\frac{21}{5}$ . $\frac{19}{8}$ + $\frac{21}{8}$ . $\frac{21}{5}$
= $\frac{21}{5}$ . ($\frac{19}{8}$ + $\frac{21}{8}$)
= $\frac{21}{5}$ . $\frac{15}{4}$
= $\frac{63}{4}$
TH2 :
(4 + $\frac{1}{5}$) . $\frac{19}{8}$ – (2 + $\frac{5}{8}$) . $\frac{21}{5}$
= 4$\frac{1}{5}$ . $\frac{19}{8}$ – 2$\frac{5}{8}$ . $\frac{21}{5}$
= $\frac{21}{5}$ . $\frac{19}{8}$ – $\frac{21}{8}$ . $\frac{21}{5}$
= $\frac{21}{5}$ . ($\frac{19}{8}$ – $\frac{21}{8}$)
= $\frac{21}{5}$ . $\frac{-1}{4}$
= $\frac{-21}{20}$
b) $\frac{25}{2}$ . (3 + $\frac{2}{7}$) – $\frac{23}{7}$ . (5 + $\frac{1}{2}$)
= $\frac{25}{2}$ . $\frac{23}{7}$ – $\frac{23}{7}$ . $\frac{11}{2}$
= $\frac{23}{7}$ . ($\frac{25}{2}$ – $\frac{11}{2}$)
= $\frac{23}{7}$ . 7
= 23.
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