Someone who hasn't seen hetalia explain this

Identify which functions are linear or non-linear. a. f(x) = x2 + 1 b. f(x) = 2x + 5 c. f(x) = x 2 + 3 d. f(x) = 3 x + 7 e. f(x) = 4x + 10 2 - 5

What are the first 4 terms in the multiplication pattern given by the formula 2×4n

What is the rate for one gallon of gasoline