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\(=\frac{3}{200}:\frac{3}{5}+\frac{3}{2}\left(\frac{4}{25}-\frac{2}{5}\right)-\frac{1}{25}.\left(\frac{7}{4}:\frac{7}{5}-\frac{5}{2}\right)\)
\(=\frac{3.5}{200.3}+\frac{3}{2}\left(\frac{4}{25}-\frac{2.5}{25}\right)-\frac{1}{25}\left(\frac{7.5}{4.7}-\frac{5}{2}\right)\)
\(=\frac{1}{40}+\frac{3}{2}\left(\frac{-6}{25}\right)-\frac{1}{25}\left(\frac{5}{4}-\frac{10}{4}\right)\)
\(=\frac{1}{40}-\frac{9}{25}+\frac{1}{20}\)
\(=\frac{1.5}{40.5}-\frac{9.8}{25.8}+\frac{1.10}{20.10}\)
\(=\frac{5-72+10}{200}=\frac{-57}{200}\)
= 1.2.3.....99/2.3.4....100
=1/100
k mk nha đáp án đúng đó
S = \(3+\frac{3}{2}+\frac{3}{2^2}+...+\frac{3}{2^9}\)
\(=3\left(1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^9}\right)\)
Đặt A = \(1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^9}\)
2A = \(2\left(1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^9}\right)\)
= \(2+1+\frac{1}{2}+....+\frac{1}{2^8}\)
\(2A-A=\left(2+1+\frac{1}{2}+...+\frac{1}{2^8}\right)-\left(1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^9}\right)\)
\(A=2-\frac{1}{2^9}\)
\(\Rightarrow S=3\left(2-\frac{1}{2^9}\right)=\frac{3.\left(2^{10}-1\right)}{2^9}\)
a) 7/2.x - (7.(18+45+47))=3
7/2.x - 7.110 = 3
7/2.x - 770 =3 => 7/2.x = 3+770=773
=> x = 773 : 7/2 = 1546/7
b) 19/3 - ( 4x+6x+x)= 4/7 : 2/5
19/3 - 11x = 10/7
11x = 19/3 - 10/7 = 103/21
x = 103/21 : 11 = 103/231
\(1)\frac{1}{2}x-\frac{3}{5}=\frac{-4}{5}\)
\(\Rightarrow\frac{1}{2}x=\frac{-4}{5}+\frac{3}{5}\)
\(\Rightarrow\frac{1}{2}x=\frac{-1}{5}\)
\(\Rightarrow x=\frac{-1}{5}:\frac{1}{2}=\frac{-1}{5}\cdot\frac{2}{1}=\frac{-2}{5}\)
\(\Leftrightarrow x=\frac{-2}{5}\)
\(2)3\frac{1}{5}-2\frac{1}{3}x=-1\frac{3}{5}+1\frac{7}{10}\)
\(\Rightarrow\frac{16}{5}-\frac{7}{3}x=-\frac{8}{5}+\frac{17}{10}\)
\(\Rightarrow\frac{7}{3}x=\frac{16}{5}-\frac{-8}{5}+\frac{17}{10}\)
\(\Rightarrow\frac{7}{3}x=\frac{16}{5}+\frac{8}{5}+\frac{17}{10}\)
\(\Rightarrow\frac{7}{3}x=\frac{24}{5}+\frac{17}{10}\)
\(\Rightarrow\frac{7}{3}x=\frac{48}{10}+\frac{17}{10}\)
Đến đây tìm được rồi nhé
3,4, áp dụng bài 1,2 rồi làm :v
k mk đi làm ơn
mk đang bị âm điểm
AI GIÚP MÌNH CÂU NÀY ĐI
xl nha mk ko chép đề dc nha
(x + 5/2) :5/2 - 3/2 = -5/4
(x + 5/2) : 5/2 = -5/4 + 3/2
(x + 5/2) : 5/2 = 1/4
(x + 5/2 ) = 1/4 x 5/2
x + 5/2 = 5/8
x = 5/8 - 5/2
x = -15/8
( X + 5/2 ) : 5/2 - 3/2 = -5/4
( X + 5/2 ) . 2/5 = -5/4 + 3/2
( X + 5/2 ) .2/5 = 1/4
X + 5/2 = 1/4 : 2/5
X + 5/2 = 5/8
X = 5/8 - 5/2
X = -15/8
X = 55/8 - 5/2
X = 35/8