Question

упростить
$25 {x}^{2} - 30xy + {9y}^{2} \\ {25x}^{2} - {9y}^{2}$
.........​

Answer 1

$25 {x}^{2} - 30xy + {9y}^{2} = \\ (5x) {}^{2} - 2 \times 5x \times 3y + (3y) {}^{2} = \\ (5x - 3y) {}^{2} \\ {25x}^{2} - {9y}^{2} = (5x) {}^{2} - (3y) {}^{2} = \\ (5x - 3y)(5x + 3y)$

Первое - квадрат разности, второе - разность квадратов