1) \(5-\left(1+\dfrac{1}{3}\right):\left(1-\dfrac{1}{3}\right)\)

\(=5-\dfrac{4}{3}:\dfrac{2}{3}\)

\(=5-\dfrac{4}{3}\cdot\dfrac{3}{2}\)

\(=5-\dfrac{4}{2}\)

\(=5-2\)

\(=3\)

b) \(\left(1+\dfrac{2}{3}-\dfrac{5}{4}\right)-\left(1-\dfrac{5}{4}\right)+2022-\dfrac{2}{3}\)

\(=1+\dfrac{2}{3}-\dfrac{5}{4}-1+\dfrac{5}{4}++2022-\dfrac{2}{3}\)

\(=\left(1-1\right)+\left(\dfrac{2}{3}-\dfrac{2}{3}\right)+\left(-\dfrac{5}{4}+\dfrac{5}{4}\right)+2022\)

\(=0+0+0+2022\)

\(=2022\)

2) \(0,7^2\cdot x=0,49^2\)

\(\Rightarrow x=\dfrac{0,49^2}{0,7^2}\)

\(\Rightarrow x=\left(\dfrac{0,49}{0,7}\right)^2\)

\(\Rightarrow x=\left(0,7\right)^2\)

\(\Rightarrow x=0,49\)

b) \(x:\left(-0,5\right)^3=\left(0,5\right)^2\)

\(\Rightarrow x=\left(0,5\right)^2\cdot\left(-0,5\right)^3\)

\(\Rightarrow x=\left(-0,5\right)^5\)

\(\Rightarrow x=-\dfrac{1}{32}\)

2:

a: =>x*0,49=0,49^2

=>x=0,49

b: =>x=(0,5)^2*(-1)*(0,5)^3=-(0,5)^5

a: \(1-\left(5\dfrac{4}{9}+a-7\dfrac{7}{18}\right):15\dfrac{3}{4}=0\)

=>\(\left(5+\dfrac{4}{9}+a-7-\dfrac{7}{18}\right):\dfrac{63}{4}=1\)

=>\(\left(a-2+\dfrac{1}{18}\right)=\dfrac{63}{4}\)

=>\(a-\dfrac{35}{18}=\dfrac{63}{4}\)

=>\(a=\dfrac{63}{4}+\dfrac{35}{18}=\dfrac{637}{36}\)

b: \(B=\left(\dfrac{2}{15}+\dfrac{5}{3}-\dfrac{3}{5}\right):\left(4\dfrac{2}{3}-2\dfrac{1}{2}\right)\)

\(=\dfrac{2+5\cdot5-3^2}{15}:\left(4+\dfrac{2}{3}-2-\dfrac{1}{2}\right)\)

\(=\dfrac{2+4^2}{15}:\left(2+\dfrac{2}{3}-\dfrac{1}{2}\right)\)

\(=\dfrac{18}{15}:\dfrac{13}{6}=\dfrac{6}{5}\cdot\dfrac{6}{13}=\dfrac{36}{65}\)

a, \(\dfrac{1}{7}\) x ( \(\dfrac{4}{3}\))² - \(\dfrac{1}{7}\) : \(\dfrac{9}{11}\) 

= \(\dfrac{1}{7}\) x  \(\dfrac{16}{9}\)   -   \(\dfrac{1}{7}\) x \(\dfrac{11}{9}\)

= \(\dfrac{1}{7}\) x ( \(\dfrac{16}{9}-\dfrac{11}{9}\))

= \(\dfrac{1}{7}\) x \(\dfrac{5}{9}\)

= \(\dfrac{5}{63}\)

b, 2x + \(\dfrac{1}{4}\) = \(\dfrac{3}{5}\)

    2x         = \(\dfrac{3}{5}-\dfrac{1}{4}\)

   2x          = \(\dfrac{7}{20}\)

     x          =  \(\dfrac{7}{20}:2\)

     x          = \(\dfrac{7}{40}\)

bạn tách từng câu ra. thế này k ai làm cho đâu

Đúng vậy

Nhờ mn làm giùm mình vs nhé c.ơn nhìu ạ

a) Đặt A=1/2 + 1/4 + 1/8 +...+ 1/256 + 1/512

\(A=\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^9}\)

\(2A=1+\frac{1}{2}+...+\frac{1}{2^8}\)

\(2A-A=\left(1+\frac{1}{2}+...+\frac{1}{2^8}\right)-\left(\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^9}\right)\)

\(A=1-\frac{1}{2^9}\)

b)\(\frac{a}{b}+\frac{4}{6}+\frac{2}{10}=\frac{3}{2}\)

\(\Rightarrow\frac{a}{b}+\frac{13}{15}=\frac{3}{2}\)

\(\Rightarrow\frac{a}{b}=\frac{19}{30}\)

\(\frac{4}{5}:\frac{a}{b}-\frac{6}{5}=\frac{3}{10}\)

\(\Rightarrow\frac{4}{5}:\frac{a}{b}=\frac{3}{2}\)

\(\Rightarrow\frac{a}{b}=\frac{8}{15}\)

Bài 4 là:

\(\dfrac{1}{2.5}\) + \(\dfrac{1}{5.8}\) +....+\(\dfrac{1}{92.95}\) + \(\dfrac{1}{95.98}\)

                  Đúng không bạn

Bạn chỉ nên đưa câu khó lên vì làm cả đề thì ko làm kịp đc