Tính bằng cách thuận tiện nhất : 3/11 × 7/19 + 3/11 × 10/19 + 3/11 × 2/19
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1) \(=\left(\frac{3}{5}+\frac{2}{5}\right).\frac{6}{11}\)
\(=1.\frac{6}{11}\)
\(=\frac{6}{11}\)
2)\(\frac{17}{25}.\left(\frac{11}{19}+\frac{6}{19}+\frac{2}{19}\right)\)
\(=\frac{17}{25}.1\)
\(=\frac{17}{25}\)
\(\frac{3}{5}+\frac{6}{11}+\frac{7}{13}+\frac{2}{5}+\frac{16}{11}+\frac{19}{13}=\left(\frac{3}{5}+\frac{2}{5}\right)\left(\frac{6}{11}+\frac{16}{11}\right)\left(\frac{7}{13}+\frac{19}{13}\right)=1+2+2=5\)
Ta có:3/5+2/5=5/5=1; 6/11+16/11=22/11=2; 7/13+19/13=26/13=2
kết quả là 1+2+2=5
a) ( 2/5 + 3/5) + 7/8
= 5/5 +7/8
= 1+ 7/8
=15/8 ( tính lại hộ mk nha, sợ ko đúng)
b)( 19/11 + 3/11 ) + 5/13
= 22/11 +5/13
= 2 + 5/13
= ...( bn tính nốt nha, vì mk ko có nháp ở đây )
k nha!!!
a) (2/5 + 7/8) + 3/5
= 2/5 + 7/8 + 3/5
= (2/5 + 3/5) + 7/8
= 1 + 7/8
= \(1\frac{7}{8}\)
b) 19/11 + (5/13 + 3/11)
= 19/11 + 5/13 + 3/11
= (19/11 + 3/11) + 5/13
= 2 + 5/13
= \(2\frac{5}{13}\)
13/19 x 23/11 - 13/19 x 8/11 - 13/19 x 4/11
= 13/19 x (23/11 - 8/11 - 4/11)
= 13/19 x 1
= 13/19
\(\dfrac{13}{19}\times\dfrac{23}{11}-\dfrac{13}{19}\times\dfrac{8}{11}-\dfrac{13}{19}\times\dfrac{4}{11}\\ =\dfrac{13}{19}\times\left(\dfrac{23}{11}-\dfrac{8}{11}-\dfrac{4}{11}\right)\\ =\dfrac{13}{19}\times1=\dfrac{13}{19}\)
a: \(=\dfrac{21}{11}+\dfrac{12}{11}+\left(-\dfrac{9}{19}-\dfrac{3}{19}-\dfrac{6}{19}\right)=3-\dfrac{18}{19}=\dfrac{39}{19}\)
b: \(=\dfrac{2}{3}+\dfrac{4}{3}+\dfrac{3}{4}+\dfrac{7}{4}+\dfrac{4}{5}+\dfrac{16}{5}=2+4+\dfrac{5}{2}=6+\dfrac{5}{2}=\dfrac{17}{2}\)
tính = cách thuận tiện nhất
a/ 5/11 nhân 7/25 trừ 15/11 nhân 1/5
b/ 3/7 nhân 25/19 trừ 1/7 nhân 18/19
a ) \(\frac{5}{11}\times\frac{7}{25}\times\frac{15}{11}\times\frac{1}{5}\)
\(=\frac{5\times7\times15\times1}{11\times25\times11\times5}\)
\(=\frac{1\times7\times3\times1}{11\times5\times11\times1}\)
\(=\frac{21}{\left(10\times5+5\times1\right)\times11}\)
\(=\frac{21}{55\times11}\)
\(=\frac{21}{55\times10+55}\)
\(=\frac{21}{550+55}\)
\(=\frac{21}{605}\) ( quá đơn giản )
\(\)
A) \(\frac{5}{11}\times\frac{7}{25}-\frac{15}{11}\times\frac{1}{5}\)
\(=\frac{5\times7}{11\times25}-\frac{15\times1}{11\times5}\)
\(=\frac{35}{10\times25+25}-\frac{15}{55}\)
\(=\frac{35}{250+25}-\frac{15}{55}\)
\(=\frac{35}{275}-\frac{15}{55}\)
\(=\frac{7}{55}-\frac{15}{55}\)
\(=\frac{7-15}{55}\)
\(=\frac{-8}{55}\)
\(\frac{19}{11}+\left(\frac{8}{13}+\frac{3}{11}\right)=\frac{19}{11}+\frac{8}{13}+\frac{3}{11}\)
\(=\left(\frac{19}{11}+\frac{3}{11}\right)+\frac{8}{13}=2+\frac{8}{13}\)
\(=\frac{26}{13}+\frac{8}{13}=\frac{34}{13}\)
\(\dfrac{3}{11}\text{×}\dfrac{7}{19}+\dfrac{3}{11}\text{×}\dfrac{10}{19}+\dfrac{3}{11}\text{×}\dfrac{1}{19}=\dfrac{3}{11}\text{×}\left(\dfrac{7}{19}+\dfrac{10}{19}+\dfrac{2}{19}\right)=\dfrac{3}{11}\text{×}1=\dfrac{3}{11}\)