Question

tìm x:

Answer 1

TA CÓ :   X(1/2.3+1/3.4+....+1/6.7)=7/3

           =>X(1/2-1/3+1/3-1/4+...+1/6-1/7)=7/3

          =>X(1/2-1/7)=7/3

          =>X.5/14=7/3

          =>X=98/15

Answer 2

x/2.3+x/3.4+x/4.5+x/5.6+x/6.7=7/3

x.(1/2.3+1/3.4+1/4.5+1/5.6+1/6.7)=7/3

x(1/2-1/3+1/3-1/4+...+1/6-1/7)=7/3

x(1/2-1/7)=7/3

x.5/14=7/3

x=98/15

(dau . la dau nhan)