17/13.18/23-4/13.18/23--5/23
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BA
5
8 tháng 3 2023
\(a.=\left(\dfrac{4}{5}.\dfrac{5}{6}\right).\dfrac{2}{3}=\dfrac{4}{6}.\dfrac{2}{3}=\dfrac{4}{9}\)
\(b.\dfrac{4}{5}.\dfrac{3}{4}+\dfrac{5}{4}.\dfrac{3}{4}=\dfrac{3}{5}+\dfrac{15}{16}=\dfrac{123}{80}\)
\(c.\left(\dfrac{11}{23}+\dfrac{9}{23}\right)+\left(\dfrac{2}{23}+\dfrac{18}{23}\right)=\dfrac{20}{23}+\dfrac{20}{23}=\dfrac{40}{23}\)
\(d.\left(\dfrac{27}{12}-\dfrac{25}{36}\right)+\left(\dfrac{17}{6}-\dfrac{15}{6}\right)=\dfrac{14}{9}+\dfrac{1}{3}=\dfrac{17}{9}\)
TG
4 tháng 4 2022
11/23 × 12/17+11/23×5/17+12/23
=(11/23+12/23) x (12/17+5/17)
=1 x 1
=1
VQ
4 tháng 4 2022
11/23 × 12/17+11/23×5/17+12/23
=11/23 × 12/17+11/23×5/17+12/23x1
=11/23 × (12/17+5/17+1)
=11/23 × 2
= 22/23
TN
28 tháng 4 2016
\(=5^2\left(\frac{5}{8.13}+\frac{5}{13.18}+...+\frac{5}{93.98}\right).\frac{392}{17}\)
\(=5^2\left(\frac{1}{8}-\frac{1}{13}+\frac{1}{13}-\frac{1}{18}+...+\frac{1}{93}-\frac{1}{98}\right)\frac{392}{17}\)
\(=25\left(\frac{1}{8}-\frac{1}{98}\right)\frac{392}{17}\)
\(=25\times\frac{45}{392}\times\frac{392}{17}\)
\(=25\times\frac{45}{17}\)
\(=\frac{1125}{17}\)
9 tháng 3 2022
TL:
8/15 x 5/6 = 40/90 = 4/9
41/20 x 3/4 = 123/80
(11/23 + 9/23) + (18/23 + 2/23) = 20/23 + 20/23 = 40/43
HT
NN
9 tháng 3 2022
\(\left(\frac{2}{3}\times\frac{4}{5}\right)\times\frac{5}{6}\) = \(\frac{2}{3}\times\frac{4}{5}\times\frac{5}{6}\)=\(\frac{2\times4\times5}{3\times5\times6}\)=\(\frac{2\times4\times5}{3\times5\times2\times3}\)=\(\frac{4}{9}\)
\(\frac{11}{23}+\frac{2}{23}+\frac{9}{23}+\frac{18}{23}\)=\(\frac{\left(11+9\right)+\left(18+2\right)}{23}\)=\(\frac{20+20}{23}\)=\(\frac{40}{23}\)
\(\frac{27}{12}+\frac{17}{6}-\frac{25}{36}-\frac{15}{6}\)=\(\left(\frac{27}{12}-\frac{25}{36}\right)+\left(\frac{17}{6}-\frac{15}{6}\right)\)=\(\frac{14}{9}+\frac{2}{6}\)=\(\frac{17}{9}\)
/HT\
18 tháng 3 2020
Có \(\frac{5^2}{3.8}+\frac{5^2}{8.13}+\frac{5^2}{13.18}+.....+\frac{5^2}{88.93}\)
=\(\frac{5.5}{3.8}+\frac{5.5}{8.13}+\frac{5.5}{13.18}+...+\frac{5.5}{88.93}\)
= \(5\left(\frac{5}{3.8}+\frac{5}{8.13}+\frac{5}{13.18}+...+\frac{5}{88.93}\right)\)
=\(5\left(\frac{1}{3}-\frac{1}{8}+\frac{1}{8}-\frac{1}{13}+\frac{1}{13}-\frac{1}{18}+.....+\frac{1}{88}-\frac{1}{93}\right)\)
=\(5\left(\frac{1}{3}-\frac{1}{93}\right)=\frac{50}{31}\)
Giải:
17/13.18/23-4/13.18/23-(-5/23)
=18/23.(17/13-4/13)+5/23
=18/23.1+5/23
=18/23+5/23
=1
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