Use Routh's stability criterion to determine how many roots 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