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) \(\dfrac{3}{5}+\dfrac{18}{9}+\dfrac{4}{10}\)

\(=0,6+2+0,4\)

\(=\left(0,6+0,4\right)+2\)

\(=1+2\)

\(=3\)

\(a\dfrac{5}{9}+\dfrac{4}{9}+\dfrac{13}{7}+\dfrac{8}{7}+\dfrac{15}{13}+\dfrac{11}{13}=\dfrac{9}{9}+\dfrac{21}{7}+\dfrac{26}{13}=1+3+2=6\)

\(b\dfrac{3}{5}+2+\dfrac{2}{5}=\dfrac{5}{5}+2=1+2=3\)

a) \(\frac{1}{3}-\frac{3}{4}-\left(\frac{-3}{5}\right)+\frac{1}{64}-\frac{2}{9}-\frac{1}{36}+\frac{1}{15}\)

=\(\left(\frac{1}{3}+\frac{3}{5}+\frac{1}{15}\right)-\left(\frac{3}{4}+\frac{2}{9}+\frac{1}{36}\right)+\frac{1}{64} \)

=\(\frac{5+9+1}{15}-\frac{27+8+1}{36}+\frac{1}{64}\)

= \(1+1+\frac{1}{64}=2\frac{1}{64}\)

1^3-3^5-(-3^5)+1^64-2^9-1^36+1^15

=1+(-3^5+3^5)+1-2^9-1+1

=2-2^9

=-510

-3/11.(-22)/66.121/15

=(-3).(-22).121

 11.66.15

=11

15

3/7.2/5.7/3.20.19/72

=3.2.7.20.19

7.5.3.72

=76

16

6/7.8/13+6/13.9/7-3/13.6/7

=6/7.8/13+6/7.9/13-3/13.6/7

=6/7.(8/13+9/13-3/13)

=6/7.14/13

=12/13

-1/4.152/11+68/4.(-1)/11

=152/4.(-1)/11+68/4.(-1)/11

=(-1)/11.(152/4+68/4)

=(-1)/11.220/4

=-110/22

-5/7.2/11+(-5)/7.9/11+12/7

=-5/7.2/11+-5/7.9/11+12/7

=-5/7.(2/11+9/11)+12/7

=-5/7.1+12/7

=(-5)/7+12/7

=7/7

=1

146/13-(18/7+68/13)

=146/13-18/7-68/13

=(146/13-68/13)-18/7

=78/13-18/7

=6-18/7

=42/7-18/7

=24/7

mik đang cần rất gấp , giúp mik vs !! 

cách 1 :

\(\frac{3}{5}\chi\frac{7}{9}+\frac{3}{5}\chi\frac{2}{9}\)

= \(\frac{3}{5}\chi\left(\frac{7}{9}+\frac{2}{9}\right)\)

= \(\frac{3}{5}\chi1\)

=  \(\frac{3}{5}\)

cách 2 : 

\(\frac{3}{5}\chi\frac{7}{9}+\frac{3}{5}\chi\frac{2}{9}\)

= \(\frac{7}{15}\)   +  \(\frac{2}{15}\)

=        \(\frac{9}{15}=\frac{3}{5}\)

\(C1:\frac{3}{5}.\frac{7}{9}+\frac{3}{5}.\frac{2}{9}\)                                            \(C2:\frac{3}{5}.\frac{7}{9}+\frac{3}{5}.\frac{2}{9}\)

\(=\frac{3}{5}\left(\frac{7}{9}+\frac{2}{9}\right)=\frac{3}{5}.1=\frac{3}{5}\)                     \(=\frac{7}{15}+\frac{2}{15}=\frac{3}{5}\)

\(C1:\frac{8}{15}:\frac{2}{11}+\frac{7}{15}:\frac{2}{11}\)                                      \(C2:\frac{8}{15}:\frac{2}{11}+\frac{7}{15}:\frac{2}{11}\)

\(=\left(\frac{8}{15}+\frac{7}{15}\right):\frac{2}{11}=1:\frac{2}{11}=\frac{11}{2}\)           \(=\frac{44}{15}+\frac{77}{30}=\frac{88}{30}+\frac{77}{30}=\frac{11}{2}\)

a)3/15*7/9+3/5*2/9

=(3/15*7/9)+(3/5*2/9)

=21/45+6/45

=27/45=3/5

c2:

=3/5*(7/9+2/9)

=3/5*9/9

=3/5

b)

=(8/15:2/11)+(7/15:2/11)

=44/15+77/30

=11/2

c2)

=(8/15+7/15):2/11

=15/15:2/11

=11/2