My assignment is due at the end of class and I'm stumped by this one question, can you guys help me out?

Which graph represents an even function?

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

A33 gram sample of a substance that's used to detect explosives has a k-value of 0.1473. n = noekt no = initial mass (at time t = 0) n = mass at time t k = a positive constant that depends on the substance itself and on the units used to measure time t = time, in days