Question: what are linearly independent functions?
Answer: One more definition: Two functions y 1 and y 2 are said to be linearly independent if neither function is a constant multiple of the other. For example, the functions y 1 = x 3 and y 2 = 5 x 3 are not linearly independent (they're linearly dependent), since y 2 is clearly a constant multiple of y 1.