Ta có : 5x + 3x - 78 = 2

=> 8x = 80

=> x= 10

đi mà hỏi thánh, viết xong đề đã mỏi tay

A=1+1/2+1/2²+1/2³+...+1/2²⁰¹⁷ 

1/2A=1/2+1/2²+1/2³+1/2⁴+...+1/2²⁰¹⁸

A-1/2A=(1+1/2+1/2²+1/2³+...+1/2²⁰¹⁷)-(1/2+1/2²+1/2³+1/2⁴+...+1/2²⁰¹⁸)

A-1/2A=1-2^2012018

1/2A=1-1/2²⁰¹⁸

A=(1-1/2²⁰¹⁸).2

A=2-2²⁰¹⁹

I get a lot of _____ out of working with young children ( enjoy )

TL:3,012 ; 3,021 ; 3,102 ; 3,120 ; 3,201 ; 3,210

                  =>   x=9:1

                  =>   x=9 

70x6+87x4+17x6

=420+348+102

=870

5+x=6

    x=6-5

    x=1

5 + x = 6

     x  =  6 - 5

     x  =     1