4. Let f be the function with f'(x) = - where f(3) = 6. 1+et x a) Write an equation for the line tangent to the curve y = f(x) and use it to approximate f(3.1). b) Use Euler's method, starting at x=3 and two steps of equal size to approximate f(3.1). Use a second derivative to show whether this is an over approximation or an under approximation. 3.1 c) Evaluate ['(x)dx and use it to evaluate (3.1).