Вправи 301 - 400 » 397

Спростіть вираз: 1) 7х(х – 4) – х(6 – х) = 7х2 – 28х – 6х + х2 = 8x2 – 34х; 2) 5аb(4а + 3b) – 10а2(2b – 4) = 20а2b + 15ab2 – 20а2b + 40а2 = = 15аb2 + 40а2; 3) xy(2x – 11y) – x(xy + 14y2) = 2x2y – 11xy2 – x2y – 14хy2 = x2y – – 25xy2; 4) 5c3(4c – 3) – 2c2(8c2 – 12) = 20c4 – 15c3 – 16c4 + 24c2 = 4c4 – 15c3 + 24c2.