1) x² + 2xy + y² = (x+y)²
2) a² + 2a + 1 = a² + 2 * a * 1 + 1² = (a+1)²
3) b² - 6b + 9 = b² - 2 * b * 3 + 3² = (b-3)²
4) c²- 10c + 25 = c² - 2 * c * 5 + 5² = (c-5)²
5) 4m² + 4m + 1 = 2²m² + 2 * 2m * 1 + 1² = (2m)² + 2 * 2m * 1 + 1² = (2m+1)²
6) 16 - 8c + c² = 4² - 2 * 4 * c + c² = (4-c)²