ГДЗ Математика 7 клас Істер (2024)

Спростіть вираз:

1) (3a – 4b)2 – (3a + 4b)2 = 9a2 – 24ab + 16b2 – (9a2 + 24ab + 16b2) = 9a2 – 24ab + 16b2 – 9a2 – 24ab – 16b2 = –48ab;
2) (2a + 3b)2 + (a – 6b)2 = 4a2 + 12ab + 9b2 + (a2 – 12ab + 36b2) = 4a2 + 12ab + 9b2 + a2 – 12ab + 36b2 = 5a2 + 45b2;
3) a(2a – 1)2 – 4a(a + 5)2 = a(4a2 – 4a + 1) – 4a(a2 +10a + 25) = 4a3 – 4a2 + a – 4a3 – 40a2 – 100a = –44a2 – 99a;
4) 12m2 – 3(2m – n)2 – 12mn = 12m2 – 3(4m2 – 4mn + n2) – 12mn = 12m2 – 12m2 + 12mn – 3n2 – 12mn = –3n2.