Use Routh's stability criterion to determine how many √s with positive real parts the following equations have:
a. s⁴ + 8s³ + 32s² + 80s + 100 = 0
b. s⁵ + 10s⁴ + 30s³ + 80s² + 344s + 480 = 0
c. s⁴ + 2s³ + 7s² = 2s + 8 = 0
d. s³ + s² + 20s + 78 = 0