\(\frac{17}{25}\times\frac{13}{19}+\frac{17}{25}\times\frac{6}{19}\)

\(=\frac{17}{25}\times\left(\frac{13}{19}+\frac{6}{19}\right)\)

\(=\frac{17}{25}\times\frac{19}{19}\)

\(=\frac{17}{25}\times1\)

\(=\frac{17}{25}\)

_HT_

\(\dfrac{17}{25}\left(\dfrac{13}{19}+\dfrac{6}{19}\right)\)

\(=\dfrac{17}{25}.1=\dfrac{17}{25}\)

a: =17/25(13/19+6/19)=17/25

b: \(=\dfrac{47}{19}\cdot\dfrac{32}{15}-\dfrac{47}{19}\cdot\dfrac{17}{15}=\dfrac{47}{19}\)

`17/25xx(13/19+6/19)`

`17/25xx1`

`17/25`

Giải:

4 + 7 + 10 + ... + 25 ( có 8 số hạng )

= ( 25 + 4 ) . 8 : 2 

= 116

học tốt!!!!

4+7+10+13+16+19+5+9+13+17+21+25 = 159 

C1)  17/25.13/19+17/25.6/19                    C2)  17/25.13/19+17/25.6/19

       =17/25.(13/19+6/19)                                =221/475+102/475

       =17/25.1=17/25                                        =17/25

Học tốt nha

\(C1:\)

\(\frac{17}{25}x\frac{13}{19}+\frac{17}{25}x\frac{6}{19}\)

\(=\frac{17}{25}x\left(\frac{13}{19}+\frac{6}{19}\right)\)

\(=\frac{17}{25}x1\)

\(=\frac{17}{25}\)

\(C2:\)

\(\frac{17}{25}x\frac{13}{19}+\frac{17}{25}x\frac{6}{19}\)

\(=\frac{221}{475}+\frac{102}{475}\)

\(=\frac{323}{475}=\frac{17}{25}\)

Bn thấy cái nào cùng mẫu hoặc dễ quy đồng thì nhóm vào 1 nhóm nha!

Xin đừng ném đá, mk chỉ nói đúng

Hội con 🐄 chúc bạn học tốt!!!

Trả lời

Bò Vinamilk 3 không (Hội con bò ) ơi

Mk thấy cách làm của bạn có j đó không đúng.

Vì mấy bài này có cả phép cộng và phép nhân nên đâu có nhóm lại được.

\(\dfrac{25^5+25^7+25^9}{5^{11}+5^{13}+5^{15}+5^{17}+5^{19}+5^{21}}\)

\(=\dfrac{5^{10}+5^{14}+5^{18}}{5^{11}+5^{13}+5^{17}+5^{19}+5^{21}}\)

\(=\dfrac{5^{10}\left(1+5^4+5^8\right)}{5^{11}\left(1+5^2+5^4+5^6+5^8+5^{10}\right)}\)

\(=\dfrac{1+5^4+5^8}{5+5^3+5^5+5^7+5^9+5^{11}}\)

\(=\dfrac{1+5^4+5^8}{\left(5+5^5+5^9\right)+\left(5^3+5^7+5^{11}\right)}\)

\(=\dfrac{1+5^4+5^8}{\left(1+5^4+5^8\right)\left(5+5^3\right)}\)

\(=\dfrac{1}{5+5^3}\)

\(=\dfrac{1}{130}\)

\(\)

1: \(\left(-\frac{25}{13}\right)+\left(-\frac{19}{17}\right)+\frac{12}{13}+\left(-\frac{25}{17}\right)\)

\(=\left(-\frac{25}{13}+\frac{12}{13}\right)+\left(-\frac{19}{17}-\frac{15}{17}\right)\)

\(=-\frac{13}{13}-\frac{34}{17}=-1-2=-3\)

2: \(\frac12-\left(-\frac13\right)+\frac{1}{23}+\frac16\)

\(=\left(\frac12+\frac13+\frac16\right)+\frac{1}{23}\)

\(=1+\frac{1}{23}=\frac{24}{23}\)

3: \(\left(-\frac37\right)\cdot\frac{5}{11}+\left(-\frac{5}{14}\right)\cdot\frac{5}{11}\)

\(=\frac{5}{11}\left(-\frac37-\frac{5}{14}\right)\)

\(=\frac{5}{11}\cdot\left(-\frac{6}{14}-\frac{5}{14}\right)=\frac{5}{11}\cdot\frac{-11}{14}=\frac{-5}{14}\)

4: \(\left(-\frac{5}{11}\right)\cdot\frac{7}{15}\cdot\frac{11}{-5}\cdot\left(-30\right)=-30\cdot\frac{7}{15}=-14\)

5: \(\left(-\frac59\right)\cdot\frac{3}{11}+\left(-\frac{13}{18}\right)\cdot\frac{3}{11}\)

\(=\frac{3}{11}\left(-\frac59-\frac{13}{18}\right)\)

\(=\frac{3}{11}\cdot\frac{-23}{18}=\frac{-23\cdot1}{11\cdot6}=-\frac{23}{66}\)

6: \(2\frac{2}{15}\cdot\frac{9}{17}\cdot\frac{3}{32}:\left(-\frac{3}{17}\right)\)

\(=\frac{32}{15}\cdot\frac{3}{32}\cdot\frac{9}{17}\cdot\frac{-17}{3}=\frac{3}{15}\cdot\frac{-9}{3}=\frac{-9}{15}=-\frac35\)

7: \(\left(-\frac34+\frac25\right):\frac37+\left(\frac35-\frac14\right):\frac37\)

\(=\left(-\frac34+\frac25+\frac35-\frac14\right):\frac37\)

\(=\left(-1+1\right):\frac37=0\)

8: \(\left(-\frac13\right)\cdot\left(-\frac{15}{19}\right)\cdot\frac{38}{45}=\frac{15}{45\cdot3}\cdot\frac{38}{19}=2\cdot\frac{1}{3\cdot3}=\frac29\)

9: \(\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\cdots+\frac{1}{19\cdot20}\)

\(=\frac12-\frac13+\frac13-\frac14+\cdots+\frac{1}{19}-\frac{1}{20}\)

\(=\frac12-\frac{1}{20}=\frac{9}{20}\)

10: \(\frac{1}{9\cdot10}-\frac{1}{8\cdot9}-\frac{1}{7\cdot8}-\cdots-\frac{1}{2\cdot3}-\frac{1}{1\cdot2}\)

\(=\frac{1}{9\cdot10}-\left(\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\cdots+\frac{1}{8\cdot9}\right)\)

\(=\frac19-\frac{1}{10}-\left(1-\frac12+\frac12-\frac13+\cdots+\frac18-\frac19\right)\)

\(=\frac19-\frac{1}{10}-\left(1-\frac19\right)=\frac19-\frac{1}{10}-\frac89=-\frac79-\frac{1}{10}=\frac{-79}{90}\)

A) =(5+(-15))+(9+(-19))+(-11)+(13+17)+(21+(-23))

=(-10)+(-10)+(-11)+20+(-2)

=((-10)+(-10))+(-11)+(-2)+20

=(-20)+(-11)+20+(-2)

=((-20)+20)+((-11)+(-2))

=0+(-13)=-13

B) doi ti !!!!! Tich cho mik nha

[25+5] + [19+21] + [13+7] + [4+16] + [17+13] + [10+9]

30+40+20+20+40+19

150+19

169

đúng ko

a] [4+16]+[7+13]+[19+21]+[5+25]+[13+17]+[10+19]

= 20+20+40+30+30+29

=169