Ответ:

№5

1) 1 - 2y + y² = (1 - y)²

2) 9m² - 6m + 1 = (3m - 1)²

3) 64m² - 112mn + 49n² = (8m - 7n)²

4) x²y² + 2xyz + z² = (xy + z)²

№6

1) x² - 4x + 4 = 0

(x - 2)² = 0

x - 2 = 0

x = 2

2) 9x² + 1 = 0

(3x - 1)(3x + 1) = 0

3x - 1 = 0 3x + 1 = 0

3x = 1 3x = -1

x = 1/3 x = -1/3

3) 49x² = 14x - 1

49x² - 14x + 1 = 0

(7x - 1)² = 0

7x - 1 = 0

7x = 1

x = 1/7