Question

Выполните действия
1. 5y(2y^3-4)
2. 8x^2-9x(x+2)
3. (c-6)(c+4)
4. (2x+y)(x-7y)

Answer 1

5y(2y³ - 4) = 5y * 2y³  + 5y * (-4) = 10y⁴ - 20y

8x² - 9x(x+2) = 8x² - 9x*x -9x * 2 = 8x² - 9x²  - 18x =
= -(9x² - 8x²) - 18x =- x²  - 18x

(c-6)(c+4) =c*c +c*4 -6c -6*4 = c² +4c - 6c  - 24 =
= c² - (6c - 4c)  - 24  = c² -2c - 24

(2x + y)(x-7y) = 2x*x +2x*(-7y) +yx +y*(-7y) = 2x² -14xy +xy -7y² =
= 2x² - (14xy - xy)  - 7y² = 2x² - 13xy - 7y²