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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!!!
\(a)x+30\%x=-1,31\)
\(\Leftrightarrow x+\frac{3x}{10}=-1,31\)
\(\Leftrightarrow10x+3x=-13,1\)
\(\Leftrightarrow13x=-13,1\Leftrightarrow x=-\frac{131}{130}\)
\(b)\left(x-\frac{1}{2}\right):\frac{1}{3}+\frac{5}{7}=9\frac{5}{7}\)
\(\Leftrightarrow\frac{2x-1}{2}.3+\frac{5}{7}=\frac{68}{7}\)
\(\Leftrightarrow\frac{6x-3}{2}=\frac{63}{7}\)
\(\Leftrightarrow\frac{6x-3}{2}=9\)
\(\Leftrightarrow6x-3=18\)
\(\Leftrightarrow x=\frac{7}{2}\)
a) x + 30%x = -1,31
(1 + 30%)x = -1,31
13/10x = -1,31
x = -1,31 : 13/10
x = -131/130
b) (x - 1/2) : 1/33 + 5/7 = 68/7
(x - 1/2) : 1/33 = 68/7 - 5/7
(x - 1/2) : 1/33 = 9
(x - 1/2) = 9 x 1/33
x - 1/2 = 3/11
x = 3/11 + 1/2
x = 17/22
c) (4,5 - 2x) . ( -11) = 11/14
(4,5 - 2x) = 11/14 : (-11)
(4,5 - 2x) = -1/14
2x = 4,5 + 1/14
2x = 32/7
x = 16/7
a,x + 30%x = -1,31
x.130%= -1,31
x = -131/130
b, (x-1/2) : 1/33 + 5/7 = 68/7
(x-1/2) . 33 = 68/7 -5/7
(x-1/2).33 = 9
x-1/2 = 9:33
x-1/2 = 3/11
x = 3/11 + 1/2
x =17/22
c,(4,5 - 2x).(-11) = 11/14
4,5 - 2x = 11/14 : (-11)
4,5 - 2x = -1/14
2x = 4,5 -(-1/14)
2x = 32/7
Dễ thế mà không làm được thì bạn nên xem lại nhé,một hai câu thì còn được chứ cả 10 câu thế kia rõ là ỷ lại rồi bạn ạ.Thân!
Bài 1 :
\(a)\frac{-17}{30}-\frac{11}{-15}+\left(-\frac{7}{12}\right)\)
\(=\frac{1}{6}+\left(-\frac{7}{12}\right)\)
\(=-\frac{5}{12}\)
\(b)-\frac{5}{9}+\frac{5}{9}:\left(1\frac{2}{3}-2\frac{1}{12}\right)\)
\(=-\frac{5}{9}+\frac{5}{9}:\left(\frac{5}{3}-\frac{25}{12}\right)\)
\(=-\frac{5}{9}+\frac{5}{9}:\left(-\frac{5}{12}\right)\)
\(=-\frac{5}{9}+\left(-\frac{2}{3}\right)\)
\(=-\frac{1}{9}\)
\(c)-\frac{7}{25}\times\frac{11}{13}+\left(-\frac{7}{25}\right)\times\frac{2}{13}-\frac{18}{25}\)
\(=-\frac{77}{325}+\left(-\frac{14}{325}\right)-\frac{18}{25}\)
\(=-\frac{7}{25}-\frac{18}{25}\)
\(=-1\)
\(a)-36:x=\frac{30}{7}\)
\(\Rightarrow x=-36:\frac{30}{7}\)
\(\Rightarrow x=-36\cdot\frac{7}{30}\)
\(\Rightarrow x=\frac{-36\cdot7}{30}\)
\(\Rightarrow x=-\frac{126}{15}\)
\(b)\frac{2}{3}\cdot x-\frac{4}{8}=\frac{1}{8}\)
\(\Rightarrow\frac{2}{3}\cdot x=\frac{1}{8}+\frac{4}{8}\)
\(\Rightarrow\frac{2}{3}\cdot x=\frac{5}{8}\)
\(\Rightarrow x=\frac{5}{8}:\frac{2}{3}=\frac{15}{16}\)
\(c)\frac{2}{7}-\frac{8}{9}x=\frac{2}{3}\)
\(\Rightarrow\frac{8}{9}x=\frac{2}{7}-\frac{2}{3}\)
\(\Rightarrow\frac{8}{9}x=\frac{6}{21}-\frac{14}{21}\)
\(\Rightarrow\frac{8}{9}x=\frac{-8}{21}\)
\(\Rightarrow x=\frac{-8}{21}:\frac{8}{9}=\frac{-72}{168}=\frac{-3}{7}\)
d, Tự làm
\(x+\frac{3}{10}x=-\frac{131}{100}\)
\(x.\left(1+\frac{3}{10}\right)=-\frac{131}{100}\)
\(x.\frac{13}{10}=-\frac{131}{100}\)
\(x=-\frac{131}{100}:\frac{13}{10}\)
\(x=-\frac{131}{130}\)