Thực hiện phép tính: ( 2x^2 + x + 4)(x^2 – x – 1 ) =
Giải thích
( 2x2 + x + 4)(x2 – x – 1 ) = 2x2.x2 + x.x2 + 4x2 – 2x2.x – x.x – 4x – 2x2 – x – 4
= 2x4 + x3 + 4x2 – 2x3 – x2 – 4x – 2x2 – x – 4
= 2x4 + ( 1 – 2 )x3 + (4 – 1 – 2 )x2 + (–4 – 1)x – 4
= 2x4 – x3 + x2 –5x – 4.