Tính bằng cách thuận tiện nhất
a)12/25+3/5+13/15
b)3/2+2/3+4/3
c)3/5+7/5+3/4
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\(1,\dfrac{12}{25}+\dfrac{3}{5}+\dfrac{13}{25}=\left(\dfrac{12}{25}+\dfrac{13}{25}\right)+\dfrac{3}{5}=1+\dfrac{3}{5}=\dfrac{8}{5}\\ 2,\dfrac{3}{2}+\dfrac{2}{3}+\dfrac{4}{3}=\dfrac{3}{2}+\left(\dfrac{2}{3}+\dfrac{4}{3}\right)=\dfrac{3}{2}+2=\dfrac{7}{2}\\ 3,\dfrac{3}{2}+\dfrac{7}{5}+\dfrac{3}{4}=\left(\dfrac{3}{2}+\dfrac{3}{4}\right)+\dfrac{7}{5}=\left(\dfrac{6}{4}+\dfrac{3}{4}\right)+\dfrac{7}{5}=\dfrac{9}{4}+\dfrac{7}{5}=\dfrac{45}{20}+\dfrac{28}{20}=\dfrac{73}{20}\)
\(a,\frac{12}{25}+\frac{3}{5}+\frac{13}{25}\)
\(=\left(\frac{12}{25}+\frac{13}{25}\right)+\frac{3}{5}\)
\(=\frac{25}{25}+\frac{3}{5}\)
\(=1+\frac{3}{5}\)
\(=\frac{8}{5}\)
\(b,\frac{3}{2}+\frac{2}{3}+\frac{4}{3}\)
\(=\frac{3}{2}+\left(\frac{2}{3}+\frac{4}{3}\right)\)
\(=\frac{3}{2}+2\)
\(=\frac{7}{2}\)
\(c,\frac{3}{5}+\frac{7}{5}+\frac{3}{4}\)
\(=\left(\frac{3}{5}+\frac{7}{5}\right)+\frac{3}{4}\)
\(=2+\frac{3}{4}\)
\(=\frac{11}{4}\)
\(\dfrac{8}{13}+\dfrac{4}{9}+\dfrac{1}{3}+\dfrac{5}{13}+3\)
\(=1+\dfrac{7}{9}+3\)
\(=4+\dfrac{7}{9}=\dfrac{43}{9}\)
a. 12/25 + 3 / 5+ 13/25 = ( 12/25+13/25)+3/5 = 1 + 3/5= 8/5
b. 3/2 + 2/3 + 4/3 = 3/2+( 2/3+4/3)= 3/2 + 2=7/2
c.3/5+7/5+3/4= (3/5+7/5)+3/4 = 2+ 3/4=11/4
chúc bn hc tốt
a. 12/25+3/5+13/25
=1+3/5
=8/5
b.3/2+2/3+4/3
=3/2+2
=7/2
c.3/5+7/5+3/4
=2+3/4
=11/4
`a: =(7/3-4/3)+11/5=16/5`
`b: =(18/13-5/13)+55/46=1+55/46=101/46`
`c: =27/25-4/9-2/25+5/9=(27/25-2/25)+(5/9-4/9)=1+1/9=10/9`
`39/16 : 5/8 - 7/16 : 5/8`
`=39/16 xx 8/5- 7/16 xx 8/5`
`=8/5 xx (39/16 - 7/16)`
`= 8/5 xx2`
`= 16/5`
__
` 4/3 xx 9/8 - 4/3 xx 3/8`
`=4/3 -(9/8 - 3/8)`
`= 4/3 xx 3/4`
`=1`
\(a,\\ \dfrac{39}{16}:\dfrac{5}{8}-\dfrac{7}{16}:\dfrac{5}{8}\\ =\dfrac{39}{16}\cdot\dfrac{8}{5}-\dfrac{7}{16}\cdot\dfrac{8}{5}\\ =\dfrac{8}{5}\cdot\left(\dfrac{39}{16}-\dfrac{7}{16}\right)=\dfrac{8}{5}\cdot2=\dfrac{16}{5}\\ b,\\ \dfrac{4}{3}\cdot\dfrac{9}{8}-\dfrac{4}{3}\cdot\dfrac{3}{8}=\dfrac{3}{2}-\dfrac{1}{2}=1\)
a) (12/25 + 13/25) + 3/5
= 25/25 + 3/5
= 25/25 + 15/25
= 40/25 = 8/5
b) 3/2 + ( 2/3 + 4/3)
= 3/2 + 1/3
= 15/6
c) ( 3/5 + 7/5) + 3/4
= 10/5 + 3/4
= 55/20 = 11/4
hok tot
nho k nhe
giải : ( ko chép lại đề ....... tự chép )
a) \(\frac{3}{5}\)+( \(\frac{12}{25}\) + \(\frac{13}{25}\))
= \(\frac{3}{5}\)+ 1
= \(\frac{8}{5}\)
b) \(\frac{3}{2}\)+ ( \(\frac{2}{3}\)+\(\frac{4}{3}\))
= \(\frac{3}{2}\)+ 2
= \(\frac{7}{2}\)
c) (\(\frac{3}{5}\)+ \(\frac{7}{5}\))+ \(\frac{3}{4}\)
= 2 + \(\frac{3}{4}\)
= \(\frac{11}{4}\)
hok tốt nha !!!
8/15+2/3=18/15=6/5 3/8+4/8=7/8 tính thuận tiện: 3/2+2/3+4/3=3/2+(2/3+4/3)=3/2+2=7/2 3/5+7/5+3/4=(3/5+7/5)+3/4=2+3/4=11/4 hình như cái đầu tiên chép sai đề????????????????