True or false: P varies directly as Q can be written as P = kQ.

true.

True. The statement "P varies directly as Q" means that P and Q have a direct proportionality relationship. This can be written as P = kQ, where k represents the constant of proportionality. In this equation, k is a fixed number that remains constant as P and Q change, and it determines the magnitude of the change in P corresponding to a certain change in Q.