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mn ơi e vít nhầm là tính rồi rút gọn mn sửa lại là rút gọn rùi tính
bn ơi mk vít nhầm là tính rồi rút gọn bn sửa lại là rút gọn rùi tính
![](https://rs.olm.vn/images/avt/0.png?1311)
a: =2/5+3/5=1
b: =1/3+2/3=1
c: =7/8+5/8=12/8=3/2
d: =2/7+3/7=5/7
\(a,\dfrac{2}{5}+\dfrac{3}{5}=\dfrac{5}{5}=1\\ b,\dfrac{1}{3}+\dfrac{2}{3}=\dfrac{3}{3}=1\\ c,\dfrac{7}{8}+\dfrac{5}{8}=\dfrac{12}{8}=\dfrac{3}{2}\\ d,\dfrac{1}{7}+\dfrac{3}{7}=\dfrac{4}{7}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{4}{5}+\frac{3}{15}=\frac{4}{5}+\frac{1}{5}=\frac{4+1}{5}=\frac{5}{5}=1\)
\(\frac{2}{3}+\frac{32}{24}=\frac{2}{3}+\frac{4}{3}=\frac{2+4}{3}=\frac{6}{3}=2\)
\(\frac{5}{6}+\frac{15}{18}=\frac{5}{6}+\frac{5}{6}=\frac{5+5}{6}=\frac{10}{6}\)
HT
![](https://rs.olm.vn/images/avt/0.png?1311)
1, Rút gọn rồi tính
a) \(\frac{4}{5}+\frac{3}{15}\)
= \(\frac{4}{5}+\frac{1}{5}\)
= \(\frac{5}{5}\)
= \(1\)
b) \(\frac{2}{3}+\frac{32}{24}\)
= \(\frac{2}{3}+\frac{4}{3}\)
= \(\frac{6}{3}\)
= \(2\)
c) \(\frac{5}{6}+\frac{15}{18}\)
= \(\frac{5}{6}+\frac{5}{6}\)
= \(\frac{10}{6}\)
= \(\frac{5}{3}\)
2, Tính rồi rút gọn
a) \(\frac{8}{15}+\frac{2}{3}\)
= \(\frac{8}{15}+\frac{10}{15}\)
= \(\frac{18}{15}\)
= \(\frac{6}{5}\)
b) \(\frac{3}{7}+\frac{4}{8}\)
= \(\frac{24}{56}+\frac{28}{56}\)
= \(\frac{52}{56}\)
= \(\frac{13}{14}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: =8/5-2/3=24/15-10/15=14/15
12/20-6/18=3/5-1/3=9/15-5/15=4/15
b: 18/21-12/27=6/7-7/9=54/63-49/63=5/63
8/12-20/50=2/3-2/5=10/15-6/15=4/15
\(a,\dfrac{8}{5}-\dfrac{18}{27}=\dfrac{8}{5}-\dfrac{2}{3}=\dfrac{14}{15}\\ \dfrac{12}{20}-\dfrac{6}{18}=\dfrac{3}{5}-\dfrac{1}{3}=\dfrac{4}{15}\\ b,\dfrac{18}{21}-\dfrac{12}{27}=\dfrac{6}{7}-\dfrac{4}{9}=\dfrac{26}{63}\\ \dfrac{8}{12}-\dfrac{20}{50}=\dfrac{2}{3}-\dfrac{2}{5}=\dfrac{4}{15}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{1}{4}+\frac{3}{5}=\frac{17}{20}\)
\(\frac{5}{2}+\frac{7}{9}=\frac{59}{18}\)
\(\frac{3}{2}+\frac{2}{3}=\frac{13}{6}\)
\(\frac{4}{5}+\frac{3}{2}=\frac{23}{10}\)
\(\frac{4}{5}+\frac{3}{15}=\frac{4}{5}+\frac{1}{5}=1\)
\(\frac{2}{3}+\frac{32}{24}=\frac{2}{3}+\frac{4}{3}=2\)
\(\frac{5}{6}+\frac{15}{18}=\frac{5}{6}+\frac{5}{6}=\frac{10}{6}=\frac{5}{3}\)
\(\frac{8}{15}+\frac{2}{3}=\frac{8}{15}+\frac{10}{15}=\frac{18}{15}=\frac{6}{5}\)
\(\frac{3}{7}+\frac{4}{8}=\frac{24}{56}+\frac{28}{56}=\frac{52}{56}=\frac{13}{14}\)
_HT_
a.4/5+3/15 = 4/5+ 3/15:3=4/5+1/5=5/5
b.2/3+32/24=2/3+32/24:8=2/3+4/3=6/3
c.5/6+15/18=5/6x3+15/18=15/18+15/18=30/18