Register Now

Login

Lost Password

Lost your password? Please enter your email address. You will receive a link and will create a new password via email.

222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: Tính nhanh ( 27x³ – 1 ) : ( 3x – 1 )

Toán Lớp 8: Tính nhanh
( 27x³ – 1 ) : ( 3x – 1 )

Comments ( 2 )

  1. ( 27 . x^3 – 1 ) : ( 3 . x – 1 )
    = ( 3^3 . x^3 – 1 ) : ( 3 . x – 1 )
    = [ ( 3 . x )^3 – 1 ] : ( 3 . x – 1 )
    = ( 3 . x – 1 ) . [ ( 3 . x )^2 + 3 . x . 1 + 1^2 ] : ( 3 . x – 1 )
    = ( 3 . x – 1 ) . ( 9 . x^2 + 3 . x + 1 ) : ( 3 . x – 1 )
    = 9 . x^2 + 3 . x + 1
     

  2. = [(3x)³ – 1] : (3x – 1)
    = (3x – 1).[(3x)² + 3x.1 + 1²] : (3x – 1)
    = (3x – 1).(9x² + 3x + 1) : (3x – 1)
    = 9x² + 3x + 1
    Dùng HĐT nha bn
     

Leave a reply

222-9+11+12:2*14+14 = ? ( )