Question

Tìm X bằng cách hợp lí nhất   X × 1999 × X = 1999 × 1997 + 1999

Answer 1

X.1999.X=1999.1997+1999

X.1999.X=1999.1997+1999.1

X.X.1999=1999.(1997+1)

X.X.1999=1999.1998

X.X=1999.1998:1999=1998

Answer 2

 X × 1999 × X = 1999 × 1997 + 1999

X^2 x 1999 = 1999 × 1997 + 1999 x 1

X^2 x 1999 = 1999 x ( 1997 + 1 )

X^2 x 1999 = 1999 x 1998

X^2 = 1999 x 1998 : 1999

X^2 = 1999 : 1999 x 1998

X^2 = 1 x 1998

X^2 = 1998