1. t² + 10t = -9
  t² + 10t + 25 = -9 + 25
  (t + 5)² = 16
  t + 5 = ±√16 = ±4
  t = -5 ± 4 = {-9, -1)
2. x² +14x = 32
  x² + 14x + 49 = 32 + 49
  (x + 7)² = 81
  x + 7 = ±9 . . . . . take the square root
  x = -7 ± 9 = {-16, 2}
3. r² - 10r = -17
  r² -10r + 25 = -17 +25
  (r -5)² = 8
  r = 5 ± 2√2