$2a + ac62 - a^2c - 2c = (ac^2 - a^2c) - (2c - 2a) = ac(c - a) - 2(c - a) = (c - a)(ac - 2)$
при $a = 1\frac{1}{3}$ и $c = -1\frac{2}{3}$:
$(c - a)(ac - 2) = (-1\frac{2}{3} - 1\frac{1}{3})(1\frac{1}{3} * (-1\frac{2}{3}) - 2) = (-\frac{5}{3} - \frac{4}{3})(\frac{4}{3} * (-\frac{5}{3}) - 2) = (-\frac{9}{3})(-\frac{20}{9} - 2) = (-3) * (\frac{-20 - 18}{9}) = -3 * (\frac{-38}{9}) = \frac{38}{3} = 12\frac{2}{3}$

$x^2y - y + xy^2 - x = (x^2y + xy^2) - (x + y) = xy(x + y) - (x + y) = (x + y)(xy - 1)$
при x = 4 и y = 0,25:
(x + y)(xy − 1) = (4 + 0,25)(4 * 0,25 − 1) = 4,25(1 − 1) = 4,25 * 0 = 0