tinhs bằng 2 cách:3-5+7-9+11-13+15
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Khách
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HK
6 tháng 3 2022
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) \(\dfrac{3}{5}+\dfrac{18}{9}+\dfrac{4}{10}\)
\(=0,6+2+0,4\)
\(=\left(0,6+0,4\right)+2\)
\(=1+2\)
\(=3\)
6 tháng 3 2022
\(a\dfrac{5}{9}+\dfrac{4}{9}+\dfrac{13}{7}+\dfrac{8}{7}+\dfrac{15}{13}+\dfrac{11}{13}=\dfrac{9}{9}+\dfrac{21}{7}+\dfrac{26}{13}=1+3+2=6\)
27 tháng 8 2017
a) \(\frac{1}{3}-\frac{3}{4}-\left(\frac{-3}{5}\right)+\frac{1}{64}-\frac{2}{9}-\frac{1}{36}+\frac{1}{15}\)
=\(\left(\frac{1}{3}+\frac{3}{5}+\frac{1}{15}\right)-\left(\frac{3}{4}+\frac{2}{9}+\frac{1}{36}\right)+\frac{1}{64} \)
=\(\frac{5+9+1}{15}-\frac{27+8+1}{36}+\frac{1}{64}\)
= \(1+1+\frac{1}{64}=2\frac{1}{64}\)
27 tháng 8 2017
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
1 tháng 5 2021
-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
SC
3
NH
4 tháng 5 2018
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 :
\(\frac{3}{5}\chi\frac{7}{9}+\frac{3}{5}\chi\frac{2}{9}\)
= \(\frac{7}{15}\) + \(\frac{2}{15}\)
= \(\frac{9}{15}=\frac{3}{5}\)
4 tháng 5 2018
\(C1:\frac{3}{5}.\frac{7}{9}+\frac{3}{5}.\frac{2}{9}\) \(C2:\frac{3}{5}.\frac{7}{9}+\frac{3}{5}.\frac{2}{9}\)
\(=\frac{3}{5}\left(\frac{7}{9}+\frac{2}{9}\right)=\frac{3}{5}.1=\frac{3}{5}\) \(=\frac{7}{15}+\frac{2}{15}=\frac{3}{5}\)
\(C1:\frac{8}{15}:\frac{2}{11}+\frac{7}{15}:\frac{2}{11}\) \(C2:\frac{8}{15}:\frac{2}{11}+\frac{7}{15}:\frac{2}{11}\)
\(=\left(\frac{8}{15}+\frac{7}{15}\right):\frac{2}{11}=1:\frac{2}{11}=\frac{11}{2}\) \(=\frac{44}{15}+\frac{77}{30}=\frac{88}{30}+\frac{77}{30}=\frac{11}{2}\)
Cách 1 :
3 - 5 + 7 - 9 + 11 - 13 + 15
= 15 + ( 3 - 5 ) + ( 7 - 9 ) + ( 11 - 13 )
= 15 - 2 -2 -2
=15 - 6
=9
Cách 2 :
3 -5 + 7 - 9 + 11 - 13 + 15
= ( 3 + 7 + 11 + 15 ) - ( 5 + 9 + 13 )
= 36 - 27
=9
cảm ơn nha