tìm x
a) x × 7 – 24,5 = 5,6
b) 48 – x × 5 = 34,5
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\(a,2x+\dfrac{5}{2}=-\dfrac{3}{5}\)
\(2x=-\dfrac{3}{5}-\dfrac{5}{2}\)
\(2x=-\dfrac{31}{10}\)
\(x=-\dfrac{31}{10}:2\)
\(x=-\dfrac{31}{20}\)
\(b,\dfrac{1}{2}:x-\dfrac{5}{6}=-\dfrac{2}{3}\)
\(\dfrac{1}{2}:x=-\dfrac{2}{3}+\dfrac{5}{6}\)
\(\dfrac{1}{2}:x=\dfrac{1}{6}\)
\(x=\dfrac{1}{2}:\dfrac{1}{6}\)
\(x=3\)
\(c,\left(312-x\right):12,6=24,5\)
\(312-x=24,5\times12,6\)
\(312-x=308,7\)
\(x=312-308,7\)
`x=3,3`
a: =>2x=-3/5-5/2=-6/10-25/10=-31/10
=>x=-31/20
b: =>1/2:x=-2/3+5/6=5/6-4/6=1/6
=>x=1/2:1/6=3
c: =>312-x=308,7
=>x=3,3
5 + ( x + 27 ) = 64
( x + 27 ) = 64 - 5 ( x + 27 ) = 59 x = 59 - 27 x = 32a) \(\Rightarrow x+27=59\Rightarrow x=32\)
b) \(\Rightarrow x-2=39\Rightarrow x=41\)
c) \(\Rightarrow x+5=-322\Rightarrow x=-327\)
d) \(\Rightarrow5x=35\Rightarrow x=7\)
e) \(\Rightarrow4\left(x-5\right)=56\Rightarrow x-5=14\Rightarrow x=19\)
f) \(\Rightarrow15+x=37\Rightarrow x=22\)
g) \(\Rightarrow7\left(13-x\right)=35\Rightarrow13-x=5\Rightarrow x=8\)
h) \(\Rightarrow10\left(x+1\right)=100\Rightarrow x+1=10\Rightarrow x=9\)
Bài 2:
a, 7,2: 2,4.\(x\) = 45
3.\(x\) = 45
\(x\) = 45: 3
\(x\) = 15
b, 9,15.\(x\) + 2,85.\(x\) = 48
\(x\).( 9,15 + 2,85) = 48
12\(x\) = 48
\(x\) = 48: 12
\(x\) = 4
c) (x.3 + 4) : 5 = 8
x.3 + 4 = 8 x 5
x.3 + 4 = 40
x.3 = 40 - 4
x.3 = 36
x = 36 : 3
x = 12
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`a)sqrt{1-4x+4x^2}+5=x-2`
`<=>\sqrt{(2x-1)^2}=x-2-5`
`<=>|2x-1|=x-7(x>=7)`
`<=>[(2x-1=x-7),(2x-1=7-x):}`
`<=>[(x=-6(ktm)),(3x=8):}`
`<=>x=8/3(ktm)`
Vậy PTVN
`b)3sqrt{12+4x}+4/7sqrt{147+49x}=3/2sqrt{48+16x}+4(x>=-3)`
`<=>6sqrt{x+3}+4sqrt{x+3}=6sqrt{x+3}+4`
`<=>4sqrt{x+3}=4`
`<=>sqrt{x+3}=1<=>x+3=1`
`<=>x=-2(tm)`
Vậy `S={-2}`
a) \(\sqrt{1-4x+4x^2}+5=x-2\Leftrightarrow\sqrt{\left(1-2x\right)^2}+5=x-2\Leftrightarrow\left|1-2x\right|=x-7\left(1\right)\)TH1: \(1-2x\ge0\Leftrightarrow x\le\dfrac{1}{2}\)
\(\left(1\right)\Leftrightarrow1-2x=x-7\Leftrightarrow3x=8\Leftrightarrow x=\dfrac{8}{3}\)(không thỏa đk)
TH2: \(1-2x< 0\Leftrightarrow x>\dfrac{1}{2}\)
\(\left(1\right)\Leftrightarrow2x-1=x-7\Leftrightarrow x=-6\)(không thỏa đk)
Vậy \(S=\varnothing\)
b) \(3\sqrt{12+4x}+\dfrac{4}{7}\sqrt{147+49x}=\dfrac{3}{2}\sqrt{48+16x}+4\Leftrightarrow6\sqrt{3+x}+4\sqrt{3+x}=6\sqrt{3+x}+4\Leftrightarrow4\sqrt{3+x}=4\Leftrightarrow\sqrt{3+x}=1\Leftrightarrow3+x=1\Leftrightarrow x=-2\)
a: x=9/2-3/7=57/14
b: =>x=7/5x5/7=1
c: =>x=11/3:3/8=11/3x8/3=88/9
a : x = \(\dfrac{9}{2}\) - \(\dfrac{3}{7}\) = \(\dfrac{57}{14}\)
b : = > x = \(\dfrac{7}{5}\) x\(\dfrac{5}{7}\) = 1
c : = > \(\dfrac{11}{3}\) : \(\dfrac{3}{8}\) = \(\dfrac{11}{3}\) x \(\dfrac{8}{3}\) = \(\dfrac{88}{9}\)
Bài 1
2/5 - 3/5 : (0,75 + 30%)
= 2/5 - 3/5 : 21/20
= 2/5 - 4/7
= -6/35
‐--------------------
Bài 2
a) x/6 = -11/3
x = -11/3 . 6
x = -22
b) 16/5 của x là 48
x = 48 : 16/5
x = 15