Вправи: 55

55. Спрости вираз.

a) (c – 5)(c + 2) + 3c + 10 = c² + 2c – 5c – 10 + 3c + 10 = c²;

б) (c³ – 2c)(2c + c³) + 4c² = 2c⁴ + c⁶ – 4c² – 2c⁴ + 4c² = c⁶;

в) (a² – a + 1)(a + 1) – a³ = a³ + 1³ – a³ = 1;

г) (x² – y)(x – y²) – y³ + xy = (x² – y)(x – y²) + у(x – y²) = (x – y²)(x² – y + y) = x²(x – y²) = x³ – x²y².