5m+5n-k(m+n) = 5(m+n) - k(m+n) = (m+n) * (5 - k)
t³ - t² - 81t + 81= (t³ - t²) - (81t - 81) = t² (t - 1) - 81 (t - 1) = (t - 1) * (t² - 81) =
= (t - 1) * (t² - 9²) = (t - 1)* (t - 9) * (t + 9)
16p² - (7-р)² = (4p)² - (7 - p)² = (4p + 7 - p) * (4p - 7 + p) = (3p + 7)*(5p - 7)