a)\(3.\left(10:x\right)=111\)

\(\Rightarrow10:x=37\)

\(x=10:37\)

\(x=\frac{10}{37}\)

b)\(3.\left(10+x\right)=111\)

\(\Rightarrow10+x=37\)

\(x=37-10\)

\(x=27\)

c)\(3+\left(10.x\right)=111\)

\(\Rightarrow10x=108\)

\(x=108:10\)

\(x=\frac{54}{5}\)

d)\(3+\left(10+x\right)=111\)

\(\Rightarrow10+x=108\)

\(x=108-10\)

\(x=98\)

P=\(\left(1-\dfrac{1}{111}\right)\left(1-\dfrac{2}{111}\right)\times...\times\left(1-\dfrac{111}{111}\right)\times...\times\left(1-\dfrac{2009}{111}\right)\)

P=\(\left(1-\dfrac{1}{111}\right)\left(1-\dfrac{2}{111}\right)\times...\times0\times...\times\left(1-\dfrac{2009}{111}\right)\)

P=0

a, \(3.\left(10.x\right)=111\Leftrightarrow\left(10.x\right)=111:3\)

\(\Leftrightarrow10.x=37\Leftrightarrow x=37:10\Leftrightarrow x=3,7\)

b,\(3.\left(10+x\right)=111\Leftrightarrow\left(10+x\right)=111:3\)

\(\Leftrightarrow10+x=37\Leftrightarrow x=37-10\Leftrightarrow x=27\)

c,\(3+\left(10.x\right)=111\Leftrightarrow\left(10.x\right)=111-3\)

\(\Leftrightarrow10.x=108\Leftrightarrow x=108:10\Leftrightarrow x=10,8\)

d,\(3+\left(10+x\right)=111\Leftrightarrow\left(10+x\right)=111-3\)

\(\Leftrightarrow10+x=108\Leftrightarrow x=108-10\Leftrightarrow x=98\)

Trả lời

a)3.(10.x)=111

       10.x =111:3

      10.x  =37

          x   =37:10

         x    =3,7

b)3.(10+x)=111

        10+x =111:3

         10+x=37

              x =37-10

              x =27

c)3+(10.x)=111

         10.x =111-3

         10.x =108

              x =108:10

             x  =10,8

d)3+(10+x )=111

        10+x   =111-3

        10+x   =108

             x    =108-10

            x     =98

Đặt A=1.2.3+2.3.4+...+111.112.113

Ta có:4A=(1.2.3+2.3.4+...+111.112.113).4

          4A=1.2.3.(4-0)+2.3.4.(5-1)+...+111.112.113.(114-110)

          4A=1.2.3.4+2.3.4.5-1.2.3.4+...+111.112.113.114-110.111.112.113

          4A=1.2.3.4-1.2.3.4+2.3.4.5-2.3.4.5+...+110.111.112.113-110.111.112.113+111.112.113.114

          4A=111.112.113.114

      =)  A= 111.112.113.114/4( chia 4)

\(A=\frac{1\times111+2\times110+3\times109+...+111\times1}{1+\left(1+2\right)+\left(1+2+3\right)+...+\left(1+2+3+...+111\right)}\)

\(A=\frac{1\times111+2\times110+3\times109+...+111\times1}{\left(1+1+...+1\right)+\left(2+2+...+2\right)+...+111}\)(\(111\)số hạng \(1\), \(110\)số hạng \(2\),...)

\(A=\frac{1\times111+2\times110+3\times109+...+111\times1}{1\times111+2\times110+3\times109+...+111\times1}\)

\(A=1\)

a)

3 . ( 10 . x ) = 111

3 . 10 . x     = 111

30 . x          = 111

x                 = \(\frac{37}{10}\)         

b) 3 + ( 10 . x ) = 111

            10 . x    = 111 - 3  

            10 . x    = 108

                   x    = 108 : 10

                   x   =  10.8

3. ( 10.x ) = 111

10.x = 111 : 3

10.x = 37

x = 37 : 10

x = 3,7

______________________

3 + ( 10.x ) = 111

10.x = 111 - 3

10.x = 108

x = 108 : 10

x = 10,8

a) \(3.\left(10.x\right)=111\)

\(10.x=37\)

\(x=\dfrac{37}{10}\)

b) \(3.\left(10+x\right)=111\)

\(10+x=37\)

\(x=27\)

c) \(3+\left(10.x\right)=111\)

\(10.x=108\)

\(x=\dfrac{54}{5}\)

d) \(3+\left(10+x\right)=111\)

\(x=111-3-10\)

\(x=98\)