Is square root of negative 6 a rational or irrational number

Given the equation f(x)=a(b)x where the initial value is 40 and the growth rate is 20% what is f(4)

Tyler enjoys the fish so much that after his birthday his family decides to take him to a famous aquarium a tank at the aquarium is similar to his tank with the scale factor of 8 how many times greater is the volume of the tank at the aquarium than the volume of tyler tank

Me i'm timed right now! there's 4 answer