7x² - 42x + 63 = 7(x² - 6x + 9) = 7(x - 3)
28x² - 84xy + 63y² = 7(4x² - 12xt + 9y²) = 7(2x - 3y)²
80 + 40a + 5a² = 5(16 + 8a + a²) = 5(4 + a)²
2a³ - 20a²b + 50ab² = 2a(a² - 10ab + 25b²) = 2a(a - 5b)²
1/8m² + m + 2 = 0
m² + 8m + 16 = 0
(m + 4)² = 0
m + 4 = 0
m = -4
1/3p² + 2p + 3 = 0
p² + 6p + 9 = 0
(p + 3)² = 0
p + 3 = 0
p = -3