5y - ( -y ( +7y ( -y ( 8y + 6 = 5y - ( -y ( +7y ( -8y² - 6у ))) = 5y - ( -y ( -54y³ - 42у² )) = 5y - 54y⁴ - 42у³
5y - ( -y ( +7y ( -y ( 8y + 6 = 5y - ( -y ( +7y ( -8y² - 6у ))) = 5y - ( -y ( -54y³ - 42у² )) = 5y - 54y⁴ - 42у³