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4/15 + 8/13 + 11/15 + 5/13
= ( 4/15 + 11/15 ) + ( 8/13 + 5/13 )
= 15/15 + 13/13
= 1 + 1
=2
\(\dfrac{5}{13}\times\dfrac{7}{11}+\dfrac{5}{13}\times\dfrac{2}{11}+\dfrac{8}{13}\times\dfrac{9}{11}\)
\(=\dfrac{5}{13}\times\left(\dfrac{7}{11}+\dfrac{2}{11}\right)+\dfrac{8}{13}\times\dfrac{9}{11}\)
\(=\dfrac{5}{13}\times\dfrac{9}{11}+\dfrac{8}{13}\times\dfrac{9}{11}\)
\(=\dfrac{9}{11}\times\left(\dfrac{5}{13}+\dfrac{8}{13}\right)\)
\(=\dfrac{9}{11}\times1\)
\(=\dfrac{9}{11}\)
a) \(20,23\times21+20,23\times80-20,23\)
\(=20,23\times\left(21+80-1\right)\)
\(=20,23\times100\)
\(=2023\)
(19+1)+(18+2)+(17+3)+(16+4)+(15+5)+(14+6)+(13+7)+(12+8)+(11+9)+20)+10
=20+20+20+20+20+20+20+20+20+20=(20*10)+10
=210
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20
=(1+19)+(2+18)+(3+17)+(4+16)+(5+15)+(6+14)+(7+13)+(8+12)+(9+11)+(10+20)
=20+20+20+20+20+20+20+20+20+30
=(20 x 9) + 30
=180 + 30
=210
tk nha
\(\frac{1}{5}+\frac{5}{7}+\frac{1}{8}+\frac{13}{8}+\frac{4}{5}+\frac{4}{7}\)
\(=\left(\frac{1}{5}+\frac{4}{5}\right)+\left(\frac{5}{7}+\frac{4}{7}\right)+\left(\frac{1}{8}+\frac{13}{8}\right)\)
\(=1+\frac{9}{7}+\frac{7}{4}\)
\(=\frac{28}{28}+\frac{36}{28}+\frac{49}{28}\)
\(=\frac{113}{28}\)
Ai k mik mik k lại
2,07 +4,15 +17,93 +5,85
= ( 2,07 +17,93) +( 4,15+5,85)
= 20 +10
= 30
Chúc bn học tốt !!!!!
\(\frac{4}{15}+\frac{8}{13}+\frac{11}{5}+\frac{5}{13}\)
\(=\left(\frac{4}{15}+\frac{11}{15}\right)+\left(\frac{8}{13}+\frac{5}{13}\right)\)
\(=1+1\)
\(=2\)
2,07 + 4,15 + 17,93 + 5,85
= (2,07 + 17,93) + (4,15 + 5,85)
= 20 + 10
= 30
4/15 + 8/13 + 11/5 + 5/13
= 4/15 + 11/15 + 8/13 + 5/13
= 15/15 + 13/13
= 1 + 1
= 2
2,07 + 4,15 + 17,93 + 5,85
= ( 4,15 + 5,85 ) + ( 2,07 + 17,93 )
= 10 + 20
= 30