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2\(\frac{2}{3}\) .x+8\(\frac{2}{3}\) =3 1/3
=8/3.x+26/3=10/3
=>x+26/3=10/3 chia 8/3
=>x+26/3=5/4
=>x=5/4-26/3
=>x=-89/12
a) x+30%x=-1.31
=> 100%x+30%x=-1.31
=>x.(100%+30%)=-1.31
=>x.13/10=-1.31=-1.31:13/10=-131/130
b) (x-1/2):1/3+5/7=9+5/7
=>(x-1/2).3+5/7=68/7
=>(x-1/2).3=68/7-5/7=9
=>x-1/2=9:3=3
=>x=3+1/2=3 1/2( hỗn số)
c) 1/2x-3/4=14/9.3/7
=>1/2x-3/4=2/3
=>1/2x=2/3+3/4=17/12
x=17/12:1/2=17/12.2=17/6
d) - 5/6 -x = 7/12+ -1/3
=>- 5/6 -x = 7/12+ -4/12=1/4
=> x = -5/6 -1/4=-13/12
e) x + 3/-15 = 1/3
=> x= 1/3 - -3/15 =1/3+3/15
=> x=5/15 + 3/15=8/15
f) (4,5 -2 x). (-1 4/7)=11/14
=> 4,5 -2x=11/14 : -3/7=11/14. -7/3=-11/6
=>-2x=-11/6-9/2= -11/6 -27/6 =-19/3
=>x= -19/3: -2x=19/6
Chúc bn thi HKII tốt!!!
Bài giải:
Câu 1: a, \(\left(-2\right).4.5.38.\left(-25\right)\)
\(=\left[\left(-2\right).5\right].\left[4.\left(-25\right)\right].38\)
\(=\left(-10\right).\left(-100\right).38\)
\(=1000.38=38000\)
b,\(\frac{1}{3}+\frac{3}{8}-\frac{7}{12}\)
\(=\left(\frac{1}{3}+\frac{3}{8}\right)-\frac{7}{12}\)
\(=\frac{17}{24}-\frac{7}{12}=\frac{1}{8}\)
c, \(\frac{-5}{8}.\frac{5}{12}+\frac{-5}{8}.\frac{7}{12}+2\frac{1}{8}\)
\(=\frac{-5}{8}.\left(\frac{5}{12}+\frac{7}{12}\right)+\frac{17}{8}\)
\(=\frac{-5}{8}.1+\frac{17}{8}\)
\(=\frac{3}{2}\)
Câu 2: a, \(x-\frac{2}{5}=0,24\)
\(x-0,4=0,24\)
\(x=0,24+0,4\)
\(\Rightarrow x=0,64\left(\frac{16}{25}\right)\)
b,\(\frac{2}{3}.x+\frac{1}{12}=\frac{1}{10}\)
\(\frac{2}{3}.x=\frac{1}{10}-\frac{1}{12}\)
\(\frac{2}{3}.x=\frac{1}{60}\)
\(x=\frac{1}{60}:\frac{2}{3}\)
\(\Rightarrow x=\frac{1}{40}\)
c, \(\left(3\frac{1}{2}-2x\right).1\frac{1}{3}=7\frac{1}{3}\)
\(\frac{7}{2}-2x=\frac{22}{3}:\frac{4}{3}\)
\(\frac{7}{2}-2x=\frac{11}{2}\)
\(2x=\frac{7}{2}-\frac{11}{2}\)
\(2x=-2\)
\(\Rightarrow x=-2:2\)
\(x=-1\)