\(\frac{2.5^{22}-9.5^{21}}{25^{10}}=\frac{2.5^2.5^{20}-9.5.5^{20}}{\left[\left(5\right)^2\right]^{10}}=\frac{5^{20}\left(2.5^2-9.5\right)}{5^{20}}=2.5^2-9.5=5\left(10-9\right)=5.1=5\)

\(\frac{2\cdot5^{22}-9\cdot5^{21}}{25^{10}}=\frac{\left(2\cdot5-9\right)\cdot5^{21}}{25^{10}}=\frac{5^{21}}{5^{20}}=5\)

B

B

B

\(\frac{2^{35}.9^{25}.5^{25}.13^{22}.7^{16}.5^{16}}{9^{26}.13^{22}5.^{22}.7^{17}.4^{17}.5^{2.9}}=2^{\left(35-2.17\right)}.9^{\left(25-26\right)}.5^{\left(25+16\right)-\left(22+2.9\right)}.13^{22-22}.7^{16-17}.\)

\(2^1.9^{-1}.5^1.13^0.7^{-1}=\frac{2.5}{9.7}=\frac{10}{63}\)

31/60

31/60

31/60 đó bạn.

a) = 3/5 

b)2/3

c) 4/3

d) 7/5

a,3/5

b,2/3

c,4/3

d,7/5

a 3/5

b 2/3

c 4/3

d 7/5

a,4/5

b=2/5

Rút gọn phân số sau:

a) \(\frac{8600-20}{10750-25}\)

\(=\frac{8580}{10725}\)

\(=\frac{4}{5}.\)

b) \(\frac{1350+10}{3375+25}\)

\(=\frac{1360}{3400}\)

\(=\frac{2}{5}.\)

Chúc bạn học tốt!

Ta có:

A = 3/4 . 8/9 . 15/16 . 24/25 . .... 899/900

   = (1.3)/(2.2) . (2.4)/(3.3) . (3.5)/(4.4).....(29.31)/(30.30) 
   = [(1.2.3...29).(3.4.5...31)]/[(2.3.4...30).(2.3.4...30)] 
   = [(1.2.3...29)/(2.3.4...30)] . [(3.4.5...31)/(2.3.4...30)]
   = (1/30) . (31/2)

   = 31/60

Bài này lp 6 mk thi huyện r

36/60

31/60

3/5 và 25/2

 3/5 và 25/2

3/5

Lời giải:

Xét tử số:

$\text{TS}=1+25^4+25^8+...+25^{28}$

$25^4.\text{TS}=25^4+25^8+...+25^{32}$

$\Rightarrow \text{TS}(25^4-1)=25^{32}-1$

$\text{TS}=\frac{25^{32}-1}{25^4-1}$

Xét mẫu số:

$\text{MS}=1+25^2+..+25^{30}$

$25^2.\text{MS}=25^2+25^4+...+25^{32}$

$\Rightarrow \text{MS}(25^2-1)=25^{32}-1$

$\Rightarrow \text{MS}=\frac{25^{32}-1}{25^2-1}$

Do đó:
$A=\frac{25^{32}-1}{25^4-1}:\frac{25^{32}-1}{25^2-1}=\frac{25^2-1}{25^4-1}$

$=\frac{25^2-1}{(25^2-1)(25^2+1)}=\frac{1}{25^2+1}$