Answer:
square roots
quadratic formula
factoring
complete the square
Step-by-step explanation:
1. In the first one, we can divide both sides by -2 and then square root it, getting x^2 = -98 so x = 7i \sqrt(2).
2. We can use the quadratic formula to find out the second one.
3. We can factor 4x^2 - 21x - 18 = 0 and get (x + 6)(4x - 3).
4. In the last one, we can complete the square, getting (x + 9)^2 + 16.
