A= \(\frac{1}{3}+\frac{1}{15}+\frac{1}{35}+\frac{1}{35}+\frac{1}{99}=\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}+\frac{1}{9.11}\)

\(2A=\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.6}+...+\frac{2}{9.11}\)

\(2A=1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{9}-\frac{1}{11}\)

\(2A=1-\frac{1}{11}=\frac{10}{11}\)

\(A=\frac{10}{11}:2=\frac{5}{11}\)

\(D=\frac{3^2}{1.4}+\frac{3^2}{4.7}+...+\frac{3^2}{13.16}\)

\(D=3.\left(\frac{3}{1.4}+\frac{3}{4.7}+...+\frac{3}{13.16}\right)\)

\(D=3.\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...+\frac{1}{13}-\frac{1}{16}\right)\)

\(D=3.\left(1-\frac{1}{16}\right)=3.\frac{15}{16}=2\frac{13}{16}\)

\(\dfrac{4^2.25^2+32.125}{2^3.5^2}\)

\(=\dfrac{\left(2^2\right)^2.\left(5^2\right)^2+2^5.5^3}{2^3.5^2}\)

\(=\dfrac{2^4.5^4+2^5.5^3}{2^3.5^2}\)

\(=\dfrac{2^3.5^2\left(2.5^2+2^2.5\right)}{2^3.5^2}\)

\(=2.5^2+2^2.5\)

\(=2.25+4.5=50+20=70\)

458 x 105 + 324 x 105 + 217 x 105 +105

= 105 x ( 458 + 324 + 217 + 1 )

= 105 x 1000

= 105000

Đây bạn nhé. Nhớ k cho mk nha

A=\(2^2-9^3+4^{-2}.16-2.5^2\)
\(=4-729+1-50=-774\)
B=\(\left(2^3.2\right).\dfrac{1}{2}+3^{-2}.3^2-7.1+5\)
\(B=2^4.\dfrac{1}{2}+1-7+5=8+1-7+5=7\)
 

 C = 2^-3 + (5²)³.5^-3 + 4^-3.16 - 2.3² - 105.(\(\dfrac{24}{51}\))⁰

C =  \(\dfrac{1}{8}\) + 5⁶.5^-3 + 4^-3.4² - 2.9 - 105.1

C =  \(\dfrac{1}{8}\) + 5³ + \(\dfrac{1}{4}\) - 18 - 105

C =  (\(\dfrac{1}{8}\) + \(\dfrac{1}{4}\))  - (105 - 125 + 18)

C = \(\dfrac{3}{8}\) - (-20 + 18)

C = \(\dfrac{3}{8}\)  + 2

C = \(\dfrac{19}{8}\)

Đặt :
\(\frac{1}{315}=a;\frac{1}{651}=b\)  thay vào A ta được :

\(A=\left(2+a\right)b-\left(3+1-b\right).3a-4ab+12a\)

\(\Leftrightarrow A=2b+ab-12a+3ab-4ab+12a\)

\(\Leftrightarrow A=2b\)

Thay \(b=\frac{1}{651}\) ta được :

\(A=\frac{2}{651}\)

Chúc bạn học tốt !!!

                         \(\frac{2^3.5^2.7^2.3^7}{49.5^3.3^6.11}\)\(=\frac{2^3.5^2.7^2.3^7}{7^2.5^3.3^6.11}=\frac{2^3.3}{5.11}=\frac{24}{55}\)

                            Ủng hộ mk nha!!!

                         Chúc các bn học tốt nha !!

\(\frac{2^3.5^2.7^2.3^7}{49.5^3.3^6.11}=\frac{2^3.5^2.7^2.3^7}{7^2.5^3.3^6.11}=\frac{2^3.1.1.3}{1.5.1.11}=\frac{24}{55}\)

Đặt 1/315=a      ;  1/651=b

2+a*b-3a(4-b)-4ab+12a

=2b=2*1/651=2/651