\(C=\frac{5^2}{1.6}+\frac{5^2}{6.11}+...+\frac{5^2}{26.31}\)

\(=5.\left(\frac{5}{1.6}+\frac{5}{6.11}+...+\frac{5}{26.31}\right)\)

\(=5.\left(1-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+...+\frac{1}{26}-\frac{1}{31}\right)\)

\(=5.\left(1-\frac{1}{31}\right)\)

\(=5.\frac{29}{31}\)

\(=\frac{145}{31}\)

sai rồi bạn ạ , phải ra 150/31 mới đúng !

hoang linh noi dung day

ĐẶT \(A=....\)

\(\Rightarrow5A=\frac{5}{1\cdot6}+\frac{5}{6\cdot11}+...+\frac{5}{26\cdot31}=\frac{1}{1}-\frac{1}{6}+\frac{1}{6}-...+\frac{1}{26}-\frac{1}{31}\)

\(\Rightarrow5A=1-\frac{1}{31}=\frac{30}{31}\Rightarrow A=\frac{30}{155}=\frac{6}{31}\)

Đặt A = ...

\(\Rightarrow A=5.\left(\frac{5}{1.6}+\frac{5}{6.11}+...+\frac{5}{26.31}\right)\)

\(\Rightarrow A=5.\left(1-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+...+\frac{1}{26}-\frac{1}{31}\right)\)

\(\Rightarrow A=5.\left(1-\frac{1}{31}\right)\)

\(\Rightarrow A=5.\frac{30}{31}\)

\(\Rightarrow A=\frac{150}{31}\)

Đặt \(S=\frac{5^2}{1.6}+\frac{5^2}{6.11}+..+\frac{5^2}{26.31}\)

\(\Leftrightarrow S=\frac{25}{1.6}+\frac{25}{6.11}+..+\frac{25}{26.31}\)

\(\Leftrightarrow\frac{1}{5}S=\frac{5}{1.6}+\frac{5}{6.11}+..+\frac{5}{26.31}\)

\(\Leftrightarrow\frac{1}{5}S=1-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+..+\frac{1}{26}-\frac{1}{31}\)

\(\Leftrightarrow\frac{1}{5}S=1-\frac{1}{31}\)

\(\Leftrightarrow\frac{1}{5}S=\frac{30}{31}\)

\(\Leftrightarrow S=\frac{30}{31}\div\frac{1}{5}\)

\(\Leftrightarrow S=\frac{150}{31}\)

1. 5³ = 5.5.5 = 125

2. 2⁷ = 2.2.2.2.2.2.2 = 128

3. 4⁴ = 4.4.4.4 = 256

4. 7³ = 7.7.7 = 343

6. 3⁵ = 243

7. 2⁶ =  64

8. 3⁴ =  81

9. 8³ =  512

11. 13² = 169

12. 11² = 121

13. 14² = 196

14. 15² = 225

16. 17² = 289

17. 18² = 324

18. 19² = 361

19. 20² = 400

21. 10⁴ = 10000

22. 10⁵ = 100000

23. 10⁶ = 1000000

24. 10⁷ = 10000000

bạn làm như bạn gia hân là đúng nhé

giải giúp mình bài 2 trên với ạ

a,\(5^3.2-100:4+2^3.5\)

= 125 . 2 - 25 + 8 . 5

= 250 - 25 + 40

= 265

b, \(6^2:9+50.2-3^3.3\)

= 36 : 9 + 100 - 27 . 3

= 4 + 100 - 81

= 23

bạn kia ko làm các ý khác à

b) \(5^3\cdot2-100:4+2^3\cdot5\)

\(=125\cdot2-25+8\cdot5\)

\(=250-25+40\)

\(=225+40=265\)

c) \(6^2:9+50\cdot2+3^3-3\)

\(=36:9+100+27-3\)

\(=4+100+27-3\)

\(=104+27-3=131-3=128\)

d) \(3^2\cdot5+2^3\cdot10-81:3\)

\(=9\cdot5+8\cdot10-27\)

\(=45+80-27\)

\(=125-27=98\)

e) \(5^{13}:5^{10}-25\cdot2^2\)

\(=5^{13-10}-5^2\cdot2^2\)

\(=5^3-\left(5\cdot2\right)^2\)

\(=125-10^2\)

\(=125-100=25\)

f) \(20:2^2+5^9:5^8\)

\(=20:4+5^{9-8}\)

\(=5+5^1=5+5=10\)

g) \(100:5^2+7\cdot3^2\)

\(=10^2:5^2+7\cdot9\)

\(=\left(10:5\right)^2+63\)

\(=2^2+63=4+63=67\)

h) \(84:4+3^9:3^7+5^0\)

\(=21+3^{9-7}+1\)

\(=21+3^2+1\)

\(=21+9+1=30+1=31\)

i) \(29-\left[16+3\cdot\left(51-49\right)\right]\)

\(=29-\left[16+3\cdot2\right]\)

\(=29-\left[16+6\right]\)

\(=29-22=7\)

j) \(\left(15^{19}:5^{17}+3\right)\cdot0:7\)

\(=\left[\left(3\cdot5\right)^{19}:5^{17}+3\right]\cdot0\)

Vì số nào nhân cho 0 cũng bằng 0 nên giá trị biểu thức trên bằng 0

k) \(7^9:7^7-3^2+2^3\cdot5\)

\(=7^{9-7}-9+8\cdot5\)

\(=7^2-9+40\)

\(=49-9+40=40+40=80\)

l) \(1200:2+6^2\cdot2^1+18\)

\(=600+36\cdot2+18\)

\(=600+72+18\)

\(=600+\left(72+18\right)=600+90=690\)

m) \(5^9:5^7+70:14-20\)

\(=5^{9-7}+5-20\)

\(=5^2+5-20\)

\(25+5-20=30-20=10\)

Những câu sau mình làm sau nhé bạn!!!!!!!

a) \(9.x-2.x=\frac{6^{27}}{6^{25}}+\frac{48}{12}\)

\(\Leftrightarrow7x=6^2+4\)

\(\Leftrightarrow7x=36+4=40\)

\(\Leftrightarrow x=\frac{40}{7}\)

Vậy : \(x=\frac{40}{7}\)

b) \(11^x=5.x+\frac{5^{31}}{5^{29}}+3.2^2-10^0\)

\(\Leftrightarrow11^x=5x+5^2+12-1\)

\(\Leftrightarrow11^x=5x+36\)

\(\Rightarrow x\in\varnothing\)

1: \(\dfrac{16^{11}\cdot5^{40}}{10^{41}}=\dfrac{2^{44}\cdot5^{40}}{2^{41}\cdot5^{41}}=\dfrac{2^3}{5^1}=\dfrac{8}{5}\)

2: \(\dfrac{3^7\cdot8^5}{6^6\cdot\left(-2\right)^{12}}=\dfrac{3^7\cdot2^{15}}{2^6\cdot3^6\cdot2^{12}}=\dfrac{3}{2^3}=\dfrac{3}{8}\)