-13/19.8/25+13/19.-17/25
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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{17}{25}\times\frac{13}{19}+\frac{17}{25}\times\frac{6}{19}\)
\(=\frac{17}{25}\times\left(\frac{13}{19}+\frac{6}{19}\right)\)
\(=\frac{17}{25}\times\frac{19}{19}\)
\(=\frac{17}{25}\times1\)
\(=\frac{17}{25}\)
_HT_
![](https://rs.olm.vn/images/avt/0.png?1311)
a: =17/25(13/19+6/19)=17/25
b: \(=\dfrac{47}{19}\cdot\dfrac{32}{15}-\dfrac{47}{19}\cdot\dfrac{17}{15}=\dfrac{47}{19}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Giải:
4 + 7 + 10 + ... + 25 ( có 8 số hạng )
= ( 25 + 4 ) . 8 : 2
= 116
học tốt!!!!
![](https://rs.olm.vn/images/avt/0.png?1311)
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
\(C1:\)
\(\frac{17}{25}x\frac{13}{19}+\frac{17}{25}x\frac{6}{19}\)
\(=\frac{17}{25}x\left(\frac{13}{19}+\frac{6}{19}\right)\)
\(=\frac{17}{25}x1\)
\(=\frac{17}{25}\)
\(C2:\)
\(\frac{17}{25}x\frac{13}{19}+\frac{17}{25}x\frac{6}{19}\)
\(=\frac{221}{475}+\frac{102}{475}\)
\(=\frac{323}{475}=\frac{17}{25}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
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!!!
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{25^5+25^7+25^9}{5^{11}+5^{13}+5^{15}+5^{17}+5^{19}+5^{21}}\)
\(=\dfrac{5^{10}+5^{14}+5^{18}}{5^{11}+5^{13}+5^{17}+5^{19}+5^{21}}\)
\(=\dfrac{5^{10}\left(1+5^4+5^8\right)}{5^{11}\left(1+5^2+5^4+5^6+5^8+5^{10}\right)}\)
\(=\dfrac{1+5^4+5^8}{5+5^3+5^5+5^7+5^9+5^{11}}\)
\(=\dfrac{1+5^4+5^8}{\left(5+5^5+5^9\right)+\left(5^3+5^7+5^{11}\right)}\)
\(=\dfrac{1+5^4+5^8}{\left(1+5^4+5^8\right)\left(5+5^3\right)}\)
\(=\dfrac{1}{5+5^3}\)
\(=\dfrac{1}{130}\)
\(\)
![](https://rs.olm.vn/images/avt/0.png?1311)
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
![](https://rs.olm.vn/images/avt/0.png?1311)
[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
\(\dfrac{-13}{19}.\dfrac{8}{25}+\dfrac{13}{19}.\dfrac{-17}{25}\)
= \(\left(\dfrac{-13}{19}+\dfrac{13}{19}\right)x\left(\dfrac{8}{25}-\dfrac{-17}{25}\right)\)
=\(0.1=0\)
sai rồi