Tìm x .
x + 4/5.9 + 4/9.13 + 4/13.17 + ... + 4/41.45 = -37/45
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Tìm x biết x + 4/5.9+4/9.13+4/13.17+...+4/41.45=-37/45
Tìm x biết x+4/5.9 + 4/9.13 +4/13.17 +...............+ 4/41.45 = -37/45
Theo đề bài ta có
x+1/5-1/9+1/9-1/13+.........+1/41-1/45=-37/45
x+(1/5-1/45)=-37/45
x+8/45=-37/45
x=-37/45 - 8/45
x=-45/45
x=-1
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Theo bài ra ta có:
x1/5-1/9+1/9-1/13+...+1/41-1/45=-37/45
x+8/45=-37/45
x=-45/45
x=-1/1
x=-1
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Tìm x, biết
x + 4/5.9 + 4/9.13 + 4/13.17 +.....+ 4/41.45 = -37/45
\(x+\frac{4}{5.9}+\frac{4}{9.13}+\frac{4}{13.17}+...+\frac{4}{41.45}=\frac{-37}{45}\)
\(x+4\left(\frac{1}{5.9}+\frac{1}{9.13}+\frac{4}{13.17}+...+\frac{1}{41.45}\right)=\frac{-37}{45}\)
\(x+4.\frac{1}{4}\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+\frac{1}{13}-\frac{1}{17}+...+\frac{1}{41}-\frac{1}{45}\right)=\frac{-37}{45}\)
\(x+1\left(\frac{1}{5}-\frac{1}{45}\right)=\frac{-37}{45}\)
\(x+\frac{8}{45}=\frac{-37}{45}\)
\(x=\frac{-37}{45}-\frac{8}{45}\)
\(x=\frac{-45}{45}=-1\)
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x + 4/5.9 + 4/9.13 + 4/13.17 + ... + 4/41.45 = -37/45
\(x+\dfrac{4}{5.9}+\dfrac{4}{9.13}+...+\dfrac{4}{41.45}=\dfrac{-37}{45}\\ \Leftrightarrow x+\dfrac{1}{5}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{13}+...+\dfrac{1}{41}-\dfrac{1}{45}=\dfrac{-37}{45}\\ \Leftrightarrow x+\dfrac{1}{5}-\dfrac{1}{45}=\dfrac{-37}{45}\\ \Leftrightarrow x+\dfrac{8}{45}=\dfrac{-37}{45}\\ \Leftrightarrow x=-1\)
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tim x
x+4/5.9+4/9.13+4/13.17+...+4/41.45=37/45
Tìm x biết:
\(x+\frac{4}{5.9}+\frac{4}{9.13}+\frac{4}{13.17}+...+\frac{4}{41.45}=\frac{-37}{45}\)
theo đề bài ta có:
\(x+\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+...+\frac{1}{41}-\frac{1}{45}=\frac{-37}{45}\)
\(x+\left(\frac{1}{5}-\frac{1}{45}\right)=\frac{-37}{45}\)
\(x+\frac{8}{45}=\frac{-37}{45}\)
\(x=\frac{-37}{45}-\frac{8}{45}\)
\(x=\frac{-45}{45}=1\)
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đặt A=4/5.9+4/9.13+4/13.17+...+4/41.45
=1/5-1/9+1/9-1/13+1/13-1/17+...+1/41-1/45
=1/5-1/45
=8/45
suy ra x+8/45=-37/45
suy ra x=-1
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x+ 1/5.9 + ... + 1/41+ 1/45 = -37/45
x + 1/5 - 1/9 + 1/9 - ......+ 1/41 - 1/45 = -37/45
x+ 1/5 - 1/45 = -37 45
x+ 8/45 =-37/45
x = -37 /45 - 8/45
x = -1
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tính
A= 5/1.3+5/3.5+5/5.7+.....+5/99.101
tìm x
x+4/5.9+4/9.13+4/13.17+...+4/41.45=-37/45
bài 1
\(2A=\left(\frac{5}{1\cdot3}+\frac{5}{3\cdot5}+...+\frac{5}{99\cdot101}\right)\cdot2\)
\(=5\left(\frac{2}{1\cdot3}+\frac{2}{3\cdot5}+...+\frac{2}{99\cdot101}\right)\)
\(=5\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{99}-\frac{1}{101}\right)\)
\(=5\left(1-\frac{1}{101}\right)\)
\(=5\cdot\frac{100}{101}\)
\(=\frac{500}{101}\Rightarrow A=\frac{500}{101}:2=\frac{250}{101}\)
bài 2:
\(x+\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+...+\frac{1}{41}-\frac{1}{45}=-\frac{37}{45}\)
\(x+\left(\frac{1}{5}-\frac{1}{45}\right)=-\frac{37}{45}\)
\(x+\frac{8}{45}=-\frac{37}{45}\)
\(x=-\frac{37}{45}-\frac{8}{45}\)
\(x=\frac{-45}{45}=-1\)
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Tìm x biết : 7/x + 4/5.9+4/9.13+4/13.17+...+4/41.45=29/45
Ta có:
\(\frac{7}{x}+\frac{4}{5.9}+\frac{4}{9.13}+...+\frac{4}{41.45}\)
\(=\frac{7}{x}+\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+...+\frac{1}{41}-\frac{1}{45}\)
\(=\frac{7}{x}+\frac{1}{5}-\frac{1}{45}\)
\(=\frac{7}{x}+\frac{9}{45}-\frac{1}{45}=\frac{7}{x}+\frac{8}{45}=\frac{29}{45}\)
\(\Rightarrow\frac{7}{x}=\frac{29}{45}-\frac{8}{45}=\frac{21}{45}=\frac{7}{15}\)
\(\Rightarrow x=15\)
Vậy x=15
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tìm các số nguyên x thoả mãn:
7/x+4/5.9+4/9.13+4/13.17+...+4/41.45=29/45
\(\frac{7}{x}+\frac{4}{5.9}+\frac{4}{9.13}+...+\frac{4}{41.45}=\frac{29}{45}\)
\(\frac{7}{x}+\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+...+\frac{1}{41}-\frac{1}{45}\right)=\frac{29}{45}\)
\(\frac{7}{x}+\left(\frac{1}{5}-\frac{1}{45}\right)=\frac{29}{45}\)
\(\frac{7}{x}+\frac{8}{45}=\frac{29}{45}\)
\(\frac{7}{x}=\frac{29}{45}-\frac{8}{45}\)
\(\frac{7}{x}=\frac{7}{15}\)
vậy x=15. k cho mình nha