b) (−2x2 + 4x + 6 ) (-1/2 x+ 1);
Giải thích
b. (−2x2 + 4x + 6 )−12x+1
= -12x(−2x2 + 4x + 6 ) + 1. (−2x2 + 4x + 6 )
= x3 − 2x2 − 3x − 2x2 + 4x + 6
= x3 + (−2x2 −2x2) + (−3x + 4x) + 6
= x3 − 4x2 + x + 6.
b. (−2x2 + 4x + 6 )−12x+1
= -12x(−2x2 + 4x + 6 ) + 1. (−2x2 + 4x + 6 )
= x3 − 2x2 − 3x − 2x2 + 4x + 6
= x3 + (−2x2 −2x2) + (−3x + 4x) + 6
= x3 − 4x2 + x + 6.