Câu hỏi của Tuyen Cao

Question

a) x2(5x3 – x - 12);

b) (3xy – x2 + y) 23x2y;

c) (4x3– 5xy + 2x)(- 12xy).

Chuong Cao · Accepted Answer

a) x2(5x3 – x - 1212) = x2. 5x3 + x2 . (-x) + x2 . (-1212)

= 5x5 – x3 – 1212x2

b) (3xy – x2 + y) 2323x2y = 2323x2y . 3xy + 2323x2y . (- x2) + 2323x2y . y

= 2x3y2 – 2323x4y + 2323x2y2

c) (4x3– 5xy + 2x)(- 1212xy) = - 1212xy . 4x3 + (- 1212xy) . (-5xy) + (- 1212xy) . 2x

= -2x4y + 5252x2y2 - x2y.Câu trả lời: a) x2(5x3 – x - 1212) = x2. 5x3 + x2 . (-x) + x2 . (-1212)

= 5x5 – x3 – 1212x2

b) (3xy – x2 + y) 2323x2y = 2323x2y . 3xy + 2323x2y . (- x2) + 2323x2y . y

= 2x3y2 – 2323x4y + 2323x2y2

c) (4x3– 5xy + 2x)(- 1212xy) = - 1212xy . 4x3 + (- 1212xy) . (-5xy) + (- 1212xy) . 2x

= -2x4y + 5252x2y2 - x2y.

Bài 1: Nhân đơn thức với đa thức