Question

Tìm x 

\(1988< 5xX-2< 1998\)

Answer 1

1988 < 5 x X - 2 < 1998

1988 < [ ( 1998 - 8 ) : 5 + 1 ] x 5 - 2 < 1998

1988 < ( 1990 : 5 + 1 ) x 5 - 2 < 1998

1988 < 399 x 5 - 2 < 1998

= > Vậy số cần tìm x = 399

Answer 2

1988 < 5 . x - 2 < 1998

1998 < { ( 1998 - 8 ) : 5 + 1 } . 5 - 2 < 1998

1988 < ( 1990 : 5 + 1 ) . 5 - 2 < 1998

1988 < ( 398 + 1 ) . 5 - 2 < 1998

1988 < 399 . 5 - 2 < 1998

=> x = 399

Vậy ...