Question

Bài 8.Thực hiện phép nhân:a) (x + 1)(1 + x -x2+ x3-x4) -(x -1)(1 + x + x2+ x3+ x4);b) ( 2b2-2 -5b + 6b3)(3 + 3b2-b)

Answer 1

a. (x + 1)(1 + x - 2x + 3x - 4x) - (x - 1)(1 + x + 2x + 3x + 4x)

= (x + 1)(1 - 2x) - (x - 1)( 1 + 10x)

= x - 2x² + 1 - 2x - x - 10x² + 1 + 10x

= x - 2x - x + 10x - 2x² - 10x² + 1 + 1

= 8x - 8x² + 2

= -8x + 8x + 2

= -(-8x + 8x + 2)

= 8x² - 8x - 2

= 8x² - 4x - 4x - 2

= 4x(2x - 1) - 2(2x + 1)

Answer 2

mình xin ý b

Answer 3

b. (2b2 - 2 - 5b + 6b3)(3 + 3b2 - b)

= (4b - 2 - 5b + 18b)(3 + 6b - b)

= (17b - 2)(3 + 5b)

= 51b + 85b² - 6 + 10b

= 85b² + 51b + 10b - 6

= \(51b\left(\dfrac{5}{3}+1\right)+6\left(\dfrac{5}{3}-1\right)\)

Answer 4

sao cậu ko nói sớm

Answer 5

(2b² - 2 - 5b + 6b³)(3 + 3b² - b)

= 6b² + 6b⁵ - 2b³ - 6 - 6b² + 2b - 15b - 15b³ + 5b² + 18b³ + 18b⁵ - 6b⁴

= 6b⁵ + 18b⁵ - 6b⁴ - 15b³ - 2b³ + 18b³ + 6b² - 6b² + 2b - 6

= 24b⁵ - 6b⁴ - 31b³ + 2b - 6