Тема: квадрат суммы и разности (3a+b) ² (7v-u) ² 12fg + (2f-3g) ² 25x² - (5x-1) ² - 2· (5a-3) ²

(3a+b) ² = (3a) ^2 + 2*3*a*b + b^2 = 9a^2 + 6ab + b^2

(7v-u) ² = (7v) ^2 - 2*7v*u + u^2 = 49v^2 - 14uv + u^2

12fg + (2f-3g) ² = 12fg + (2f) ^2 - 2*2f*3g + (3g) ^2 = 12fg + 4f^2 - 12fg + 9g^2 = 4f^2 + 9g^2

25x² - (5x-1) ² = 25 x² - ((5x) ² - 2*5x*1+1²) = 25x² - (25x² - 10x + 1) = 25x² - 25x² + 10x-1 = 10x-1

-2· (5a-3) ² = - 2 ((5a) ^2-2*3*5a+3^2) = - 2 * (25a^2-30a+9) = - 50a^2+60a-18