tinh bằn cách thuận tiện
4/15+8?13+11/5+5/13
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a) \(\dfrac{5}{9}+\dfrac{13}{7}+\dfrac{15}{13}+\dfrac{8}{7}+\dfrac{4}{9}+\dfrac{11}{13}\)
\(=\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+\left(\dfrac{13}{7}+\dfrac{8}{7}\right)+\left(\dfrac{15}{13}+\dfrac{11}{13}\right)\)
\(=1+3+2\)
\(=6\)
b) \(\dfrac{3}{5}+\dfrac{18}{9}+\dfrac{4}{10}\)
\(=0,6+2+0,4\)
\(=\left(0,6+0,4\right)+2\)
\(=1+2\)
\(=3\)
\(a\dfrac{5}{9}+\dfrac{4}{9}+\dfrac{13}{7}+\dfrac{8}{7}+\dfrac{15}{13}+\dfrac{11}{13}=\dfrac{9}{9}+\dfrac{21}{7}+\dfrac{26}{13}=1+3+2=6\)
\(\frac{4}{15}+\frac{8}{13}+\frac{11}{5}+\frac{5}{13}\)
\(=\left(\frac{4}{15}+\frac{11}{15}\right)+\left(\frac{8}{13}+\frac{5}{13}\right)\)
\(=1+1\)
\(=2\)
2,07 + 4,15 + 17,93 + 5,85
= (2,07 + 17,93) + (4,15 + 5,85)
= 20 + 10
= 30
\(\frac{13}{19}\times\frac{23}{11}-\frac{13}{19}\times\frac{8}{11}-\frac{13}{19}\times\frac{4}{11}\)
\(=\frac{13}{19}\times\left(\frac{23}{11}-\frac{8}{11}-\frac{4}{11}\right)\)
\(=\frac{13}{19}\times1\)
\(=\frac{13}{19}\)
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
\(\dfrac{5}{13}\times\dfrac{7}{11}+\dfrac{5}{13}\times\dfrac{2}{11}+\dfrac{8}{13}\times\dfrac{9}{11}\)
\(=\dfrac{5}{13}\times\left(\dfrac{7}{11}+\dfrac{2}{11}\right)+\dfrac{8}{13}\times\dfrac{9}{11}\)
\(=\dfrac{5}{13}\times\dfrac{9}{11}+\dfrac{8}{13}\times\dfrac{9}{11}\)
\(=\dfrac{9}{11}\times\left(\dfrac{5}{13}+\dfrac{8}{13}\right)\)
\(=\dfrac{9}{11}\times1\)
\(=\dfrac{9}{11}\)
a) \(20,23\times21+20,23\times80-20,23\)
\(=20,23\times\left(21+80-1\right)\)
\(=20,23\times100\)
\(=2023\)
tính bằng cách thuận tiện nhất
a,4/15 x 7/8 + 4/15 x 2/9
b, 13/29 x 23/11 -13/19 x 8/11 - 13/19 x 4/11
\(\frac{4}{15}+\frac{8}{13}+\frac{11}{15}+\frac{5}{13}\)
\(=\left(\frac{4}{15}+\frac{11}{15}\right)+\left(\frac{8}{13}+\frac{5}{13}\right)\)
\(=\frac{15}{15}+\frac{13}{13}\)
\(=1+1\)
\(=2\)
Chúc bạn học tốt nha !!!
\(\frac{4}{15}+\frac{8}{13}+\frac{11}{15}+\frac{5}{13}\)
\(=\left(\frac{4}{15}+\frac{11}{15}\right)+\left(\frac{8}{13}+\frac{5}{13}\right)\)
\(=1+1\)
\(=2\)
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) 5 / 13 xx 4 / 15 xx 13 = [ 5 xx 4 xx 13 ] / [ 13 xx 5 xx 3 ] = 4 / 3`
`b) ( 3 / 7 + 5 / 2 ) xx 7 / 5 = 3 / 7 xx 7 / 5 + 5 / 2 xx 7 / 5 = 3 / 5 + 7 / 2 = 6 / 10 + 35 / 10 = 41 / 10`
`c) 1 / 5 xx 11 / 18 + 11 / 18 xx 3 / 5 = 11 / 18 xx ( 1 / 5 + 3 / 5 ) = 11 / 18 xx 4 / 5 = [ 11 xx 2 xx 2 ] / [ 2 xx 9 xx 5 ] = 22 / 45`
\(a,\dfrac{5}{13}\times\dfrac{4}{15}\times13=\dfrac{4}{3}\)
\(b,\left(\dfrac{3}{7}+\dfrac{5}{2}\right)\times\dfrac{7}{5}=\left(\dfrac{6}{14}+\dfrac{35}{14}\right)\times\dfrac{7}{5}=\dfrac{41}{14}\times\dfrac{7}{15}=\dfrac{41}{30}\)
\(c,\dfrac{1}{5}\times\dfrac{11}{18}+\dfrac{11}{18}\times\dfrac{3}{5}=\dfrac{11}{18}\times\left(\dfrac{1}{5}+\dfrac{3}{5}\right)=\dfrac{11}{18}\times\dfrac{4}{5}=\dfrac{22}{45}\)
4/15 + 8/13 + 11/15 + 5/13
= ( 4/15 + 11/15 ) + ( 8/13 + 5/13 )
= 15/15 + 13/13
= 1 + 1
=2
là 11/5 chứ ko phải là 11/15