Решение:
- а) \( 6.2x^2 - (3.8x + 2.7x^2) = 6.2x^2 - 3.8x - 2.7x^2 = (6.2 - 2.7)x^2 - 3.8x = 3.5x^2 - 3.8x \)
- б) \( 2.5 - (y^2 + 3) - (1.2 - 0.8y^2) = 2.5 - y^2 - 3 - 1.2 + 0.8y^2 = (0.8 - 1)y^2 + (2.5 - 3 - 1.2) = -0.2y^2 - 1.7 \)
Ответ: а) 3.5x² - 3.8x; б) -0.2y² - 1.7.