1) (t² - 2t +4)/((2t - 1)(2t + 1)) · t(2t + 1)/((t + 2)(t² - 2t + 4)) = t/((2t - 1)(t + 2))
2) t/((2t - 1)(t + 2)) - (t + 2)/(t(2t - 1)) = (t² - t² - 4t - 4)/(t(2t - 1)(t + 2)) =
= (-4t -4)/(t(2t - 1)(t + 2))
3) (-4t -4)/(t(2t - 1)(t + 2)) · (t(t + 2)/7) = (-4t - 4)/(7(2t - 1))
4) (-4t - 4)/(7(2t - 1)) + (10t + 1)/(7(2t - 1)) = (-4t - 4 + 10t + 1)/(7(2t - 1)) =
= (6t - 3)/(7(2t - 1)) = 3(2t - 1)/(7(2t - 1)) = 3/7
Ответ: 3/7