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Mình chỉ làm cho bạn câu d và e thôi
d) ( 1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 +....... +1/99 - 1/100 ) . (x - 3)=1
( 1 - 1/100 ) . (x - 3 )=1
99/100.(x -3)=1
x - 3 = 1:99/100
x - 3 =100/99
x = 100/99 + 3
x = 397/99
e) (1/2 . (1 - 1/3 + 1/3 - 1/5 + 1/5 -1/7 +.....+1/99 - 1/101 ) . (x+2) =3/101
(1/2 . ( 1 - 1/101 ).(x+2)=3/101
(1/2 . 100/101 ) . (x + 2) =3/101
100/202 . ( x + 2 )= 3/101
50/101 . (x + 2 ) = 3/101
x + 2 = 3/101 :50/101
x+2=3/50
x =3/50-2
x= -97/100
a) \(x:\left(-\frac{1}{3}\right)^3=-\frac{1}{3}\)
\(\Rightarrow x=\left(-\frac{1}{3}\right).\left(-\frac{1}{3}\right)^3\)
\(\Rightarrow x=\left(-\frac{1}{3}\right)^4\)
\(\Rightarrow x=\frac{1}{81}\)
Vậy \(x=\frac{1}{81}.\)
b) \(\frac{3}{4}:\frac{41}{99}=x:\frac{75}{90}\)
\(\Rightarrow\frac{297}{164}=x:\frac{75}{90}\)
\(\Rightarrow x=\frac{297}{164}.\frac{75}{90}\)
\(\Rightarrow x=\frac{495}{328}\)
Vậy \(x=\frac{495}{328}.\)
c) \(x+\left|-\frac{1}{2}\right|=3\frac{1}{3}-4\frac{1}{2}\)
\(\Rightarrow x+\frac{1}{2}=\frac{10}{3}-\frac{9}{2}\)
\(\Rightarrow x+\frac{1}{2}=-\frac{7}{6}\)
\(\Rightarrow x=\left(-\frac{7}{6}\right)-\frac{1}{2}\)
\(\Rightarrow x=-\frac{5}{3}\)
Vậy \(x=-\frac{5}{3}.\)
Chúc bạn học tốt!
2: =>2x-1/4=5/6-1/2x
=>5/2x=5/6+1/4=13/12
=>x=13/30
3: =>3x-5/6=2/3-1/2x
=>3,5x=2/3+5/6=4/6+5/6=9/6=3,2
hay x=32/35
Bài 1c)
\(\frac{1}{3}+x=\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+...+\frac{1}{110}\)
\(\frac{1}{3}+x=\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+...+\frac{1}{10.11}\)
\(\frac{1}{3}+x=\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{10}-\frac{1}{11}\)
\(\frac{1}{3}+x=\frac{1}{3}-\frac{1}{11}=\frac{11}{33}-\frac{3}{33}=\frac{8}{33}\)
\(x=\frac{8}{33}-\frac{1}{3}=\frac{8}{33}-\frac{11}{33}=\frac{-3}{33}=\frac{-1}{11}\)
\(=\frac{3}{2}.\frac{4}{3}.\frac{5}{4}.....\frac{100}{99}=\frac{\left(3.4.5.....99\right).100}{2.\left(3.4.5....99\right)}=\frac{100}{2}=50\)
Bài 2:
a, 1/3 + 1/2 : x = -4
=> 1/2 : x = -4 - 1/3
=> 1/2 : x = -13/3
=> x = 1/2 ; -13/3
=> x = -3/26
Vậy x = -3 / 26
Bài 2:
b, x2 - 4x = 0
=> x.(x - 4) =0
=> x=0 hoặc x - 4 = 0
x - 4= 0 => x=4
Vậy x=0 và x=4