75%*x-x=-1/3/4
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a) \(\frac{1}{2}x+\frac{3}{5}\left(x-2\right)=3\)
0,5 x + 0,6 ( x - 2 ) = 3
0,5 x + 0.6 x - 1,2 = 3
1,1 x = 4,2
x = \(\frac{42}{11}\)
Kết luận:
b) \(\frac{1}{3}x-0,5x=0,75\)
\(\frac{1}{3}x-\frac{1}{2}x=\frac{3}{4}\)
\(-\frac{1}{6}x=\frac{3}{4}\)
\(x=-\frac{9}{2}\)
Kết luận:
c) \(\frac{3}{-2}x-0,5x=75\%\)
-1,5x - 0,5x = 0,75
-2x = 0,75
x = -0,375
Kết luận:
d) \(-\frac{2}{5}x+\frac{1}{4}=75\%-\frac{3}{4}x\)
-0,4 x + 0,25 = 0,75 - 0,75 x
-0,4 x + 0,75 x = 0,75 - 0,25
0,35 x = 0,5
x = \(\frac{10}{7}\)
Kết luận:
\(a,\frac{1}{2}x+\frac{3}{5}\left(x-2\right)=3\)
\(\frac{1}{2}x+\frac{3}{5}x-\frac{6}{5}=3\)
\(\left(\frac{1}{2}+\frac{3}{5}\right)x-\frac{6}{5}=3\)
\(\frac{11}{10}x-\frac{6}{5}=3\)
\(\frac{11}{10}x=\frac{21}{5}\)
\(x=\frac{42}{11}\)
\(b,\frac{1}{3}x-\frac{1}{2}x=\frac{3}{4}\)
\(\left(\frac{1}{3}-\frac{1}{2}\right)x=\frac{3}{4}\)
\(\frac{-1}{6}x=\frac{3}{4}\)
\(x=\frac{-9}{2}\)
\(c,\frac{3}{-2}x-\frac{1}{2}x=75\%\)
\(\left(\frac{3}{-2}-\frac{1}{2}\right)x=\frac{3}{4}\)
\(-2x=\frac{3}{4}\)
\(x=\frac{-3}{8}\)
\(\frac{-2}{5}x+\frac{1}{4}=75\%-\frac{3}{4}x\)
\(\frac{-2}{5}x+\frac{3}{4}x=\frac{3}{4}-\frac{1}{4}\)
\(\left(\frac{-2}{5}+\frac{3}{4}\right)x=\frac{1}{2}\)
\(\frac{7}{20}x=\frac{1}{2}\)
\(x=\frac{10}{7}\)
a: \(12:\dfrac{3}{4}+75\%\cdot\dfrac{1}{2}-16\cdot50\%\)
\(=12\cdot\dfrac{4}{3}+\dfrac{3}{4}\cdot\dfrac{1}{2}-16\cdot0,5\)
\(=16-8+\dfrac{3}{8}\)
\(=8,375\)
b: \(75\%\cdot4+22,5:3-1\dfrac{3}{5}\)
\(=0,75\cdot4+7,5-1,6\)
\(=3+7,5-1,6\)
=10,5-1,6
=8,9
\(\frac{1}{3}.x+\frac{3}{4}.x-75\%=-\frac{21}{4}\)
\(\frac{1}{3}.x+\frac{3}{4}.x-\frac{3}{4}=-\frac{21}{4}\)
\(x.\left(\frac{1}{3}+\frac{3}{4}\right)=-\frac{21}{4}+\frac{3}{4}\)
\(x.\frac{13}{12}=-\frac{9}{2}\)
\(x=-\frac{9}{2}:\frac{13}{12}\)
\(x=-\frac{54}{13}\)
=> x.(1/3+3/4) -75/100=-21/4
=> x .13/12 - 3/4 =21/4
=> x. 13/12 =21/4 + 3/4
=> x.13/12 =6
=> x = 6 : 13/12
=> x = 72/13
vậy x= 72/13
\(\frac{1}{3}.x+\frac{3}{4}.x-75\%=\frac{-51}{4}\)
\(x.\left(\frac{1}{3}+\frac{3}{4}\right)-\frac{3}{4}=\frac{-51}{4}\)
\(x.\left(\frac{4}{12}+\frac{9}{12}\right)=\frac{-51}{4}+\frac{-3}{4}\)
\(x.\frac{13}{12}=\frac{-54}{4}=\frac{-27}{2}\)
\(x=\frac{-27}{2}:\frac{13}{12}=\frac{-27}{2}.\frac{2}{13}=\frac{-27.2}{2.13}=\frac{-27.1}{1.13}=\frac{-27}{13}\)
Xin lỗi cho mình sửa lại
\(\frac{1}{3}.x+\frac{3}{4}.x-75\%=\frac{-51}{4}\)
\(x.\left(\frac{1}{3}+\frac{3}{4}\right)-\frac{3}{4}=\frac{-51}{4}\)
\(x.\left(\frac{4}{12}+\frac{9}{12}\right)=\frac{-51}{4}+\frac{3}{4}=\frac{-48}{4}\)
\(x.\frac{13}{12}=-12\)
\(x=-12:\frac{13}{12}=12.\frac{12}{13}=\frac{-12.12}{13}=\frac{-144}{13}\)
a: =25(15+45*3)
=25*150
=3750
b: \(=-10\left(25+75-50\right)=-10\cdot50=-500\)
c: =>3^x-2=27
=>x-2=3
=>x=5
d: =>2x-5=-4
=>2x=1
=>x=1/2
e: =>2(x-1)^2=32
=>(x-1)^2=16
=>x-1=4 hoặc x-1=-4
=>x=-3 hoặc x=5
f: =>25(x+3)=75
=>x+3=3
=>x=0
a, 7\(x\) - \(x\) = 521 : 519 + 3.22.7
6\(x\) = 53 + 3.4.7
6\(x\) = 125 + 12.7
6\(x\) = 125 + 84
6\(x\) = 209
\(x\) = 209 : 6
\(x\) = \(\dfrac{209}{6}\)
b; 11\(x\) - 7\(x\) + 34 : 33 = 54 + 2\(x\)
4\(x\) + 3 = 625 + 2\(x\)
4\(x\) - 2\(x\) = 625 - 3
2\(x\) = 622
\(x\) = 622 : 2
\(x\) = 311
c; 75 - 5.(\(x-3\))3 = 700
5.(\(x\) - 3)3 = 700 - 75
5.(\(x\) - 3)3 = - 625
(\(x\) - 30)3 = - 625 : 5
(\(x\) - 30)3 = - 125
(\(x-3\))3 = (-5)3
\(x\) - 3 = - 5
\(x\) = - 5 + 3
\(x\) = -2
d, 3.(2\(x\) - 1)2 = 75
(2\(x\) - 1)2 = 75 : 3
(2\(x\) - 1)2 = 25
\(\left[{}\begin{matrix}2x-1=-5\\2x-1=5\end{matrix}\right.\)
\(\left[{}\begin{matrix}2x=-5+1\\2x=5+1\end{matrix}\right.\)
\(\left[{}\begin{matrix}2x=-4\\2x=6\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=-2\\x=3\end{matrix}\right.\)
\(a,x.\frac{3}{4}-1=\frac{2}{75}\)
\(x.\frac{3}{4}=\frac{77}{75}\)
\(x=\frac{77}{75}:\frac{3}{4}=\frac{308}{225}\)
\(b,3-x:\frac{2}{3}=75\)
\(x:\frac{2}{3}=-72\)
\(x=-72.\frac{2}{3}=-48\)
Bài 1:
\(A=\frac{1}{\left(1+2\right)}+\frac{1}{\left(1+2+3\right)}+\frac{1}{\left(1+2+3+4\right)}\)\(+\frac{1}{\left(1+2+3+4+5\right)}+...+\)\(\frac{1}{\left(1+2+3+...+10\right)}\)
\(A=\frac{1}{3}+\frac{1}{6}+....+\frac{1}{55}\)
\(A=2\left(\frac{1}{6}+\frac{1}{12}+....+\frac{1}{110}\right)\)
\(A=2\left(\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{10.11}\right)\)
\(A=2\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+....+\frac{1}{10}-\frac{1}{11}\right)\)
\(A=2.\left(\frac{1}{2}-\frac{1}{11}\right)\)
\(A=\frac{9}{11}\)
Bài 2 :
2) Tử số = 11 x 13 x 15 + 3 x 3 x 3 x 11 x 13 x 15 + 5 x 5 x 5 x 11 x 13 x 15 + 9 x 9 x 9 x 11 x 13 x 15
= (1 + 3 x 3 x 3 + 5 x 5 x 5 + 9 x 9 x9) x 11 x 13 x 15 = (1+27+125+ 729) x 11 x 13 x 15
Mẫu số = 11 x 13 x 17 + 3 x 3 x 3 x 13 x 15 x 19 + 5 x 5 x 5 x 13 x 15 x 17 + 9 x 9 x 9 x 13 x 15 x 17 lớn hơn 11 x 13 x 15 + 3 x 3 x 3 x 13 x 15 x 17 + 5 x 5 x 5 x 13 x 15 x 17 + 9 x 9 x 9 x 13 x 15 x 17
= (1 + 3 x 3 x 3 + 5 x 5 x 5 + 9 x 9 x9) 13 x 15 x 17 = (1+27+125+729) x 13 x 15 x 17
\(\Rightarrow A< \frac{\left(1+27+125+729\right)\times11\times13\times15}{\left(1+27+125+729\right)\times13\times15\times17}\)
\(=\frac{11}{17}\)
\(=\frac{1111}{1717}=B\)
Vậy \(A=B\)
\(75\%x-x=1-\frac{3}{4}\)
\(\Rightarrow\frac{75}{100}.x-x=\frac{1}{4}\)
\(\Rightarrow\frac{3}{4}x-x=\frac{1}{4}\)
\(\Rightarrow x.\left(\frac{3}{4}-1\right)=\frac{1}{4}\)
\(\Rightarrow x.\frac{-1}{4}=\frac{1}{4}\)
\(\Rightarrow x=-1\)