1. The problem statement, all variables and given/known data Let g be a twice differentiable function with g'(x)>0 and g''(x)>0 for all real numbers x, such that g(4)=12 and g(5)=18. Of the following, which is a possible value for g(6)? a. 15 b. 18 c. 21 d. 24 e. 27 Answer: e. 27 2. Relevant equations 3. The attempt at a solution I guess the first question is the first line of the question. "Let g be a twice-differentiable function with g'(x)>0 and g''(x)>0" means the first and second derivative of g(x) is positive, right? They gave me g(4)=12 and g(5)=18. Therefore, I can find the function by plugging it into y-y1 = m(x-x1, find m, and then find b. 12-18 = m(4-5) -6 = m(-1) m=6 12 = 6(4) + b b = -12 y= 6x-12 Since they want g(6), I plugged in 6 for x. y= 6(6)-12 y= 24 Though that is answer d, it is incorrect. I guess my problem might come from the first sentence. They told me g'(x) and g''(x) is positive, but I don't know how that helps me.