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\(26\times8+4\times13-10\times26\)
\(=26\times8+2\times2\times13-10\times26\)
\(=26\times8+2\times26-10\times26\)
\(=26\times\left(8+2-10\right)\)
\(=26\times0\)
\(=0\)
#Đang Bận Thở
a)12/17+19/17+8/17=(12/17+8/17)+19/17=20/17+19/17=39/17
b)2/5+7/12+13/12=2/5+(7/12+13/12)=2/5+5/3=31/15
~HT~
k cho mình nha
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`(12/26+5/8)+7/13`
`=(6/13+5/8)+7/13`
`=(6/13+7/13)+5/8`
`=1+5/8=13/8`
`(12/26 +5/8) +7/13 `
`= 6/13 + 5/8 + 7/13`
`= (6/13 + 7/13) + 5/8`
`= 13/13 + 5/8`
`= 1 + 5/8 `
`= 8/8 + 5/8 `
`= 13/8`
42 x 2 x 7 x 5 =
= ( 42 x 7 ) x ( 2 x 5 )
= 294 x 10
= 2 940
\(\frac{5}{11}.\frac{7}{25}+\frac{15}{11}.\frac{1}{5}\)
\(=\frac{5}{11}.\frac{7}{25}+\frac{5}{11}.3.\frac{1}{5}\)
\(=\frac{5}{11}.\frac{7}{25}+\frac{5}{11}.\frac{3}{5}\)
\(=\frac{5}{11}\left(\frac{7}{25}+\frac{3}{5}\right)\)
\(=\frac{5}{11}\left(\frac{7}{25}+\frac{15}{25}\right)\)
\(=\frac{5}{11}.\frac{22}{25}=\frac{2}{5}\)
Lời giải:
$1+2+3+....+25$
$=(1+25)+(2+24)+(3+23)+(4+22)+(5+21)+(6+20)+(7+19)+(8+18)+(9+17)+(10+16)+(11+15)+(12+14)+13$
$=\underbrace{26+26+26+...+26}_{12}+13$
$=26\times 12+13=325$
=6/13+7/13+5/8=1+5/8=13/8