Odpowiedź:
zad 9
a)
6x(2x- 1) + 4x(4 - 3x) = 12x² - 6x + 16x - 12x² = 10x = 10 * (- 4,2) = - 42
b)
(y - 2)(y + 3) - y² = y² - 2y + 3y - 6 - y² = y - 6 = - 1 1/7 - 6 = - 7 1/7
c)
a(3a + b) - 2a² = 3a² + ab - 2a² = a² +ab = 5² + 5 * ( - 3) = 25 - 15 = 10
d)
m(2m + 6) - 3(1 + 2m) = 2m² + 6m - 3 - 6m = 2m² - 3 = 2 * (1/n)² - 3 =
= 2 * (- 1/5)² - 3 = 2 * 1/25 - 3 = 2/25 - 3 = 2/25 - 2 25/25 = - 2 23/25
