Question

tìm số tự nhiên x sao cho : 

4/7 < x/10 < 5/7 

Answer 1

=>40/70<7x/70<50/70

=>\(7x\in\left\{42;49\right\}\)

hay \(x\in\left\{6;7\right\}\)

Answer 2

4/7 < x/10 < 5/7

=> 40/70 < 7x/70 < 50/70

=> 7x = [ 41 ; 42 ; 43 ; 44 ; 45 ; 46 ; 47 ; 48 ; 49 ]

=< x = [ 41/7 ; 6 ; 43 /7 ; 44/7 ;45/7 ;46/7 ;47/7; 48/7; 7]

Answer 3

4/7 < x/10 < 5/7

40/70 < 7x/10 < 50/70

40 < 7x < 50

40 : 7 < x < 50 : 7

5,714 < x < 7,143

x = 6;7