Let z = [y] and y = [x] - x, where [.] is the greatest integer function. If x is not an integer but positive, then what is the value of z? 

If f(x) = 4x + 1 and g(x) = kx + 2 such that f o g(x) = g o f(x), then what is the value of k?  

What is the minimum value of the function f(x) = log₁₀(x² + 2x + 11)? 

If f(2x) = 4x² + 1, then for how many real values of x will f(2x) be the GM of f(x) and f(4x)?