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\(\dfrac{17}{2}\) x \(\dfrac{3}{5}\) + \(\dfrac{3}{5}\) x \(\dfrac{1}{2}\) + \(\dfrac{3}{5}\)
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10 tháng 5 2022
a: =(0,43+0,57)+(0,25+0,75)+(0,64+0,46)
=1+1+1,1=3,1
b: =56,3(2,4+8,9-1,3)=56,3x10=563
H
8 tháng 2 2023
`a, 3-(x+5/7 )=9/21`
`=>x+5/7= 3-9/21`
`=>x+5/7= 63/21-9/21`
`=>x+5/7= 54/21`
`=>x= 54/21-5/7`
`=>x= 54/21 - 15/21`
`=>x= 39/21`
`=>x= 13/7`
`b, x/2+ x/5 = 17/10`
`=> (5x)/10 + (2x)/10=17/10`
`=> 7x/10=17/10`
`=> 7x.10=10.17`
`=>7x.10=170`
`=>7x=170:10`
`=>7x=17`
`=>x=17/7`
`c, 1/2x + 1/3 -1= 3 1/3`
`=> 1/2x + 1/3 -1= 10/3`
`=> 1/2x + 1/3=10/3+1`
`=> 1/2x + 1/3=10/3 + 3/3`
`=> 1/2x + 1/3=13/3`
`=>1/2 x= 13/3 -1/3`
`=> 1/2x= 12/3`
`=> 1/2x= 4`
`=>x= 4 :1/2`
`=>x= 4 xx 2`
`=>x=8`
VT
8 tháng 2 2023
\(a,3-\left(x+\dfrac{5}{7}\right)=\dfrac{9}{21}\\ x+\dfrac{5}{7}=3-\dfrac{9}{21}\\ x+\dfrac{5}{7}=\dfrac{18}{7}\\ x=\dfrac{18}{7}-\dfrac{5}{7}\\ x=\dfrac{13}{7}\\ b,\dfrac{x}{2}+\dfrac{x}{5}=\dfrac{17}{10}\\ \dfrac{5x}{10}+\dfrac{2x}{10}=\dfrac{17}{10}\\ \dfrac{7x}{10}=\dfrac{17}{10}\\ 7x=17\\ x=\dfrac{17}{7}\\ c,\dfrac{1}{2}x+\dfrac{1}{3}-1=3\dfrac{1}{3}\\ \dfrac{1}{2}x+\dfrac{1}{3}-1=\dfrac{10}{3}\\ \dfrac{1}{2}x+\dfrac{1}{3}=\dfrac{10}{3}+1\\ \dfrac{1}{2}x+\dfrac{1}{3}=\dfrac{13}{3}\\ \dfrac{1}{2}x=\dfrac{13}{3}-\dfrac{1}{3}\\ \dfrac{1}{2}x=4\\ x=4:\dfrac{1}{2}\\ x=10\)
8 tháng 7 2021
1) Ta có: \(\left(-\dfrac{2}{3}\right)^2\cdot\dfrac{-9}{8}-25\%\cdot\dfrac{-16}{5}\)
\(=\dfrac{4}{9}\cdot\dfrac{-9}{8}-\dfrac{1}{4}\cdot\dfrac{-16}{5}\)
\(=\dfrac{-1}{2}+\dfrac{4}{5}\)
\(=\dfrac{-5}{10}+\dfrac{8}{10}=\dfrac{3}{10}\)
2) Ta có: \(-1\dfrac{2}{5}\cdot75\%+\dfrac{-7}{5}\cdot25\%\)
\(=\dfrac{-7}{5}\cdot\dfrac{3}{4}+\dfrac{-7}{5}\cdot\dfrac{1}{4}\)
\(=\dfrac{-7}{5}\left(\dfrac{3}{4}+\dfrac{1}{4}\right)=-\dfrac{7}{5}\)
3) Ta có: \(-2\dfrac{3}{7}\cdot\left(-125\%\right)+\dfrac{-17}{7}\cdot25\%\)
\(=\dfrac{-17}{7}\cdot\dfrac{-5}{4}+\dfrac{-17}{7}\cdot\dfrac{1}{4}\)
\(=\dfrac{-17}{7}\cdot\left(\dfrac{-5}{4}+\dfrac{1}{4}\right)\)
\(=\dfrac{17}{7}\)
4) Ta có: \(\left(-2\right)^3\cdot\left(\dfrac{3}{4}\cdot0.25\right):\left(2\dfrac{1}{4}-1\dfrac{1}{6}\right)\)
\(=\left(-8\right)\cdot\left(\dfrac{3}{4}\cdot\dfrac{1}{4}\right):\left(\dfrac{9}{4}-\dfrac{7}{6}\right)\)
\(=\left(-8\right)\cdot\dfrac{3}{16}:\dfrac{54-28}{24}\)
\(=\dfrac{-3}{2}\cdot\dfrac{24}{26}\)
\(=\dfrac{-72}{52}=\dfrac{-18}{13}\)
22 tháng 7 2021
a) Ta có: \(-3\dfrac{1}{4}\cdot x-75\%+\dfrac{3x}{2}=-1.2:\dfrac{-9}{10}-1\dfrac{1}{4}\)
\(\Leftrightarrow\dfrac{-13x}{4}-\dfrac{3}{4}+\dfrac{3x}{2}=\dfrac{-6}{5}\cdot\dfrac{10}{-9}-\dfrac{5}{4}\)
\(\Leftrightarrow\dfrac{-13x-3+6x}{4}=\dfrac{4}{3}-\dfrac{5}{4}\)
\(\Leftrightarrow\dfrac{-7x-3}{4}=\dfrac{1}{12}\)
\(\Leftrightarrow-7x-3=\dfrac{1}{3}\)
\(\Leftrightarrow-7x=\dfrac{10}{3}\)
hay \(x=-\dfrac{10}{21}\)
22 tháng 7 2021
b) Ta có: \(\dfrac{5}{3}+\dfrac{5}{15}+\dfrac{5}{35}+...+\dfrac{5}{x\left(x+2\right)}=2\dfrac{8}{17}\)
\(\Leftrightarrow\dfrac{5}{2}\left(\dfrac{2}{3}+\dfrac{2}{15}+\dfrac{2}{35}+...+\dfrac{2}{x\left(x+2\right)}\right)=2\dfrac{8}{17}\)
\(\Leftrightarrow\dfrac{5}{2}\left(1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+...+\dfrac{1}{x}-\dfrac{1}{x+2}\right)=2+\dfrac{8}{17}\)
\(\Leftrightarrow\left(1-\dfrac{1}{x+2}\right)=\dfrac{42}{17}:\dfrac{5}{2}\)
\(\Leftrightarrow\dfrac{x+1}{x+2}=\dfrac{42}{17}\cdot\dfrac{2}{5}=\dfrac{84}{85}\)
\(\Leftrightarrow85x+85=84x+168\)
\(\Leftrightarrow x=83\)
15 tháng 5 2022
a: (x+1/2)(2/3-2x)=0
=>x+1/2=0 hoặc 2/3-2x=0
=>x=-1/2 hoặc x=1/3
b: 
c: \(\Leftrightarrow x\cdot\left(\dfrac{13}{4}-\dfrac{7}{6}\right)=\dfrac{5}{12}+\dfrac{5}{3}=\dfrac{5}{12}+\dfrac{20}{12}=\dfrac{25}{12}\)
\(\Leftrightarrow x=\dfrac{25}{12}:\dfrac{39-14}{12}=\dfrac{25}{25}=1\)
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
23 tháng 2 2023
a, \(\dfrac{x-1}{21}\) = \(\dfrac{3}{x+1}\)
( x-1)(x+1) = 21.3
x2 + x - x -1 = 63
x2 = 63 + 1
x2 = 64
x = + - 8
b, 2\(\dfrac{1}{2}\)x + x = 2\(\dfrac{1}{17}\)
x( \(\dfrac{5}{2}\) + 1) = \(\dfrac{35}{17}\)
x = \(\dfrac{35}{17}\) : ( \(\dfrac{5}{2}\)+1)
x = \(\dfrac{35}{17}\) x \(\dfrac{2}{7}\)
x = \(\dfrac{10}{17}\)
c, (x + \(\dfrac{1}{4}\) - \(\dfrac{2}{3}\) ) : ( 2 + \(\dfrac{1}{6}\) - \(\dfrac{1}{4}\)) = \(\dfrac{7}{46}\)
(x - \(\dfrac{5}{12}\)): \(\dfrac{23}{12}\) = \(\dfrac{7}{46}\)
(x - \(\dfrac{5}{12}\)) = \(\dfrac{7}{46}\) x \(\dfrac{23}{12}\)
x - \(\dfrac{5}{12}\) = \(\dfrac{7}{12}\)
x = \(\dfrac{7}{12}\) + \(\dfrac{5}{12}\)
x = 1
d, 2\(\dfrac{1}{3}\)x - 1\(\dfrac{3}{4}\)x + \(2\dfrac{2}{3}\) = 3\(\dfrac{3}{5}\)
x( \(\dfrac{7}{3}\) - \(\dfrac{7}{4}\)) + \(\dfrac{8}{3}\) = \(\dfrac{18}{5}\)
x\(\dfrac{7}{12}\) = \(\dfrac{18}{5}\) - \(\dfrac{8}{3}\)
x\(\dfrac{7}{12}\) = \(\dfrac{14}{15}\)
x = \(\dfrac{14}{15}\) : \(\dfrac{7}{12}\)
x = \(\dfrac{8}{5}\)
NH
11 tháng 3 2023
bạn tách một câu vài câu hỏi chứ đừng gộp như thế này ko ai trả lời đâu
11 tháng 3 2023
a: =>\(4x-5=2x-2+x=3x-2\)
=>x=3
b: \(\Leftrightarrow7x-35=3x+6\)
=>4x=41
=>x=41/4
c: =>(2x+5)(x+5)-2x^2=0
=>2x^2+10x+5x+25-2x^2=0
=>15x=-25
=>x=-5/3
e: \(\Leftrightarrow\dfrac{11}{x}=\dfrac{9x-36+2x+2}{\left(x+1\right)\left(x-4\right)}\)
=>11(x^2-3x-4)=x(11x-34)
=>11x^2-33x-44=11x^2-34x
=>x=44
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