Question 3 For this question a written answer is required. Which of following functions are convex, and why (please list the method you use to define the convexity)? (a)ax +b(a,beR) (b)ear, a ER (C)x (0 sa sl) (d) log x(xeR-) (e)x (a 21) (f)x" (a s0) (g)xlog x(x ERP) (h)[x] (x R, p 21) Hint: There are four methods: 1. definition; 2. sum; 3. linear transformation 4. whether a twice differentiable function