г) -q + q² - 7 = q² - 2 * 1/2 * q + 1/4 - 1/4 - 7 = (q - 1/2)² - 29/4

д) a² + 1/2a + 4 = a² + 2 * 1/4 * a + 1/16 - 1/16 + 4 = (a + 1/4)² + 63/16

и) x² - 5x = x² - 2 * 5/2 * x + 25/4 - 25/4 = (x - 5/2)² - 25/4