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)? 

Which one of the following is correct regarding $\rm \lim\limits_{x\rightarrow 3}\frac{|x-3|}{x-3}$?

What is the maximum value of a cos x + b sin x + c?