Is 6.08276 an irrational number

Find the nonpermissible replacement for binthis expression. b2/5b +5

A6 ounce bottle of dressing costs $1.56 a 14 ounce bottle costs $3.36 a 20 ounce bottle costs $5.60 which has the lowest cost per ounce

Find the volume of the wedge cut from the first octant by the cylinder z=12-3y^2 and the plane x+y=2.