1) 5(3-5a)² - 5(3а-7)(3а+7) = 5(9-30а+25а²) - 5(9а²-49) = 5(9-30а+25а²-9а²+49) = 5(16а²-30а+58)
2) (а+1)² + 3(а-1)² - 5(а+1)(а-1) = а²+2а+1+3(а²-2а+1) - 5(а²-1) = а²+2а+1+3а²-6а+3-5а²+5 = -а²-4а+9
3) (m-1)² - 4(m+1)² - 6(m+1)(m-1) = m²-2m+1 - 4(m²+2m+1) - 6(m²-1) = m²-2m+1m-4m²-8m-4-6m²+6 = -9m²-10m+3
4) 5(1-y)² - (3+у)² - 3(1-у)(1+у) = 5(1-2у+у²) - (9+6у+у²) - 3(1-у²) = 5-10у+5у²-9-6у-у²-3+3у² = 7у²-16у-7
5) 5(1+m)(1-m) - (2-m)² - 8(1-m)² = 5(1-m²) - (4-4m+m²) - 8(1-2m+m²) = 5-5m²-4+4m-m²-8+16m-8m² = -14m²+20m-7