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\(a)\) \(2x-5=21\)
\(\Leftrightarrow\) \(2x=21+5\)
\(\Leftrightarrow\) \(2x=26\)
\(\Leftrightarrow\) \(x=26:2\)
\(\Leftrightarrow\) \(=13\)
\(b)\) \(\frac{3}{4}+\frac{1}{4}x=\frac{5}{6}\)
\(\Leftrightarrow\) \(\frac{1}{4}x=\frac{5}{6}-\frac{3}{4}\)
\(\Leftrightarrow\) \(\frac{1}{4}x=\frac{1}{12}\)
\(\Leftrightarrow\) \(x=\frac{1}{3}\)
`1/2 xx x +3/2 =7`
`=> 1/2 xx x = 7-3/2`
`=> 1/2 xx x = 14/2 -3/2`
`=> 1/2 xx x = 11/2`
`=> x= 11/2 :1/2`
`=> x=11/2 xx2`
`=> x= 22/2`
`=>x=11`
Vậy `x=11`
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`3/2 xx x -2/7 xx(x-7/2)=18`
`=> 3/2 xx x -2/7x + 1=18`
`=> (3/2 -2/7 )x+ 1 =18`
`=> 17/14 x=18-1`
`=> 17/14x=17`
`=>x=17:17/14`
`=> x=17 xx 14/17`
`=>x=14`
a) \(\dfrac{1}{2}\times x+\dfrac{3}{2}=7\)
\(\dfrac{1}{2}\times x=7-\dfrac{3}{2}\)
\(\dfrac{1}{2}\times x=\dfrac{11}{2}\)
\(x=\dfrac{11}{2}\div\dfrac{1}{2}\\ x=\dfrac{11}{2}\times2\\ x=\dfrac{22}{2}=11\)
b) \(\dfrac{3}{2}\times x-\dfrac{2}{7}\times\left(x-\dfrac{7}{2}\right)=18\)
\(\dfrac{3}{2}\times x-\left(\dfrac{2}{7}x-1\right)=18\)
\(\dfrac{3}{2}\times x-\dfrac{2}{7}x+1=18\)
\(\dfrac{3}{2}x-\dfrac{2}{7}x+1=18\)
\(\dfrac{17}{14}x+1=18\)
\(\dfrac{17}{14}x=18-1\)
\(\dfrac{17}{14}x=17\)
\(x=17\div\dfrac{17}{14}\)
\(x=17\times\dfrac{14}{17}\)
\(x=14\)
\(x\cdot\frac{3}{2}+\frac{7}{2}\cdot x=2020\)
\(x\cdot\left(\frac{3}{2}+\frac{7}{2}\right)=2020\)
\(x\cdot5=2020\)
\(x=404\)
\(x:\frac{1}{3}+\frac{2}{3}=2\)
\(x\cdot3=2-\frac{2}{3}\)
\(x\cdot3=\frac{4}{3}\)
\(x=\frac{4}{9}\)
a) X x 48 + 52 x X =160
X x ( 48+52) = 160
X x 100 = 160
X = 8/5
b) 7 x ( 8+2xX) =210
8+2xX = 30
2xX= 22
X= 11
c) X x 56 + 44 x X+285 x X =130
X x ( 56+44+285)= 130
X x 385 =130
X = 26/77
d) (x-12) x 17 : 11= 51
( x-12) x17 =561
x-12 = 33
x= 45
e) 915 x X +285 x X =48
X x( 915+285) = 48
X x 1200 = 48
X =1/25
\(48x+52x=160\)
\(x.\left(48+52\right)=160\)
\(100x=160\)
\(x=\frac{160}{100}\)
\(x=1,6\)
Vậy \(x=1,6\)
Đăng ít thôi b
=>th1:x-7=0 =>x=7
=>th2:2x2-8=0=>2x2=8=>x=2
xx là 2 số hả bn.góp ý:muốn ghi dấu nhân bạn ấn shift+8 nha.