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
= \(2\frac{5}{13}\)
\(a,\left(\frac{2}{5}+\frac{7}{8}\right)+\frac{3}{5}\)
\(=\frac{2}{5}+\frac{7}{8}+\frac{3}{5}\)
\(=\left(\frac{2}{5}+\frac{3}{5}\right)+\frac{7}{8}\)
\(=1+\frac{7}{8}\)
\(=\frac{15}{8}\)
\(b,\frac{19}{11}+\left(\frac{5}{13}+\frac{3}{11}\right)\)
\(=\frac{19}{11}+\frac{5}{13}+\frac{3}{11}\)
\(=\left(\frac{19}{11}+\frac{3}{11}\right)+\frac{5}{13}\)
\(=2+\frac{5}{13}\)
\(=\frac{31}{13}\)
