1)
(х³ + 8) / (6х² + 11х - 2) =
= (х + 2)(х² - 2х + 4) / (6х² + 12х - х - 2) =
= (х + 2)(х² - 2х + 4) / ((6х² + 12х) - (х + 2)) =
= (х + 2)(х² - 2х + 4) / (6х*(х + 2) - (х + 2)) =
= (х + 2)(х² - 2х + 4) / (х + 2)(6х - 1) =
= (х² - 2х + 4) / (6х - 1)
2)
(х² + 2х - 15) / (4х - х² - 3) = (х + 5)(х - 3) / (-(х - 1)(х - 3)) =
= (х + 5) / (-(х - 1) = (х + 5) / (1 - х)