Vậy giải bài này đi
1/2x + 150%x = 2014
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\(2x+\left(x-3\right)=\frac{1}{2}\)
\(2x+x-3=\frac{1}{2}\)
\(3x-3=\frac{1}{2}\)
\(3x=\frac{1}{2}+3\)
\(3x=\frac{7}{2}\)
\(x=\frac{7}{2}:3\)
\(\Rightarrow x=\frac{7}{6}\)
\(A=1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^9}\)
\(2A=2\left(1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^9}\right)\)
\(2A=2+\frac{2}{2}+\frac{2}{2^2}+...+\frac{2}{2^9}\)
\(2A=2+1+\frac{1}{2}+...+\frac{2}{2^8}\)
=>\(A=2+\frac{-1}{29}\)
=>\(A=\frac{57}{29}\)
\(A=1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^9}\)
=> \(2A=2+1+\frac{1}{2}+...+\frac{1}{2^8}\)
=> \(A=\left(2+1+\frac{1}{2}+...+\frac{1}{2^8}\right)-\left(1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^9}\right)\)
=> \(A=2+1+\frac{1}{2}+...+\frac{1}{2^8}-1-\frac{1}{2}-\frac{1}{2^2}-...-\frac{1}{2^9}\)
=> \(A=2-\frac{1}{2^9}\)
Tìm x
a) | 2x + 1 | = | x - 3 |
TH1: 2x + 1 = x - 3 ⇒ 2x - x = -3 - 1 ⇒ x = -4
TH2: 2x + 1 = -x + 3 ⇒ 2x + x = 3 - 1 ⇒ 3x = 2 ⇒ x = 2/3
Vậy x = -4 hoặc x = 2/3
b) (2x + 1/3 ) 2 = 1/100 (sửa đề)
TH1: 2x + 1/3 = 1/10 ⇒ 2x = 1/10 - 1/3 = -7/30 ⇒ x = -7/30 : 2 = -7/60
TH2: 2x + 1/3 = -1/10 ⇒ 2x = -1/10 - 1/3 = -13/30 ⇒ x = -13/30 : 2 = -13/60
Vậy x = -7/60 hoặc x = -13/60
\(A=\frac{3n+2}{n-2}=\frac{3\left(n-2\right)+8}{n-2}=3+\frac{8}{n-2}\)
A nguyên khi \(\frac{8}{n-2}\) nguyên
=> \(8⋮n-2\) => \(n-2\inƯ\left(8\right)\)
=> \(n-2\in\left\{1;2;4;8;-1;-2;-4;-8\right\}\)
=> \(n\in\left\{3;4;6;10;1;0;-2;-4;-6\right\}\)
x=\(\left(1-\frac{1}{2}\right)\).\(\left(1-\frac{1}{3}\right)\).\(\left(1-\frac{1}{4}\right)\)...\(\left(1-\frac{1}{10}\right)\)
x=\(\frac{1}{2}\).\(\frac{2}{3}\).\(\frac{3}{4}\)...\(\frac{9}{10}\)
x=\(\frac{1}{10}\)
vậy x=\(\frac{1}{10}\)
\(B=\frac{3^2}{8.11}+\frac{3^2}{11.14}+...+\frac{3^2}{197.200}\)
\(B=3.\left(\frac{1}{8.11}+\frac{1}{11.14}+...+\frac{1}{197.200}\right)\)
\(B=3.\left(\frac{1}{8}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+...+\frac{1}{197}-\frac{1}{200}\right)\)
\(B=3.\left(\frac{1}{8}-\frac{1}{200}\right)\)
\(B=3.\frac{3}{25}\)
\(\Rightarrow B=\frac{9}{25}\)
\(B=\frac{3^2}{8.11}+\frac{3^2}{11.14}+...+\frac{3^2}{197.200}.\)
\(=3\left(\frac{3}{8.11}+\frac{3}{11.14}+...+\frac{3}{197.200}\right)\)
\(=3\left(\frac{11-8}{8.11}+\frac{14-11}{11.14}+...+\frac{200-197}{197.200}\right)\)
\(=3\left(\frac{1}{8}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+...+\frac{1}{197}-\frac{1}{200}\right)\)
\(=3\left(\frac{1}{8}-\frac{1}{200}\right)\)
\(=3\cdot\frac{3}{25}\)
\(=\frac{9}{25}\)
\(\frac{1}{2}x+150\%x=2014\)
\(\frac{1}{2}x+\frac{3}{2}x=2014\)
\(\left(\frac{1}{2}+\frac{3}{2}\right).x=2014\)
\(2.x=2014\)
\(\Rightarrow x=1007\)
\(\frac{1}{2}x+150\%x=2014\)
=>\(\frac{1}{2}x+\frac{3}{2}x=2014\)
=>x(\(\frac{1}{2}+\frac{3}{2}\))=2014
=>x.2=2014
=>x=1007
vậy x=1007