Suppose m1 is a two-tape tm and m2 is the ordinary tm

Question

Problem

Suppose M₁ is a two-tape TM, and M₂ is the ordinary TM constructed in to simulate M₁. If M₁ requires n moves to process an input string x, give an upper bound on the number of moves M₂ requires in order to simulate the processing of x. Note that the number of moves M₁ has made places a limit on the position of its tape head. Try to make your upper bound as sharp as possible.