Question

Derivs :(

Answer 1

http://gyazo.com/da79c8768e1e4ff28a282298e1a5d458

Answer 2

For the function to be differentiable at the point x=1 two things have to be true: the two formulas have to produce the same value at x=1 and they must have the same slope at x=1.

Begin by finding the value at x=1. Plug 1 into the formula 3x^2 and you get 3. So the coordinates of the point where these formulas join up are (1,3).

Now you need the slope. Find the derivative of 3x^2 and evaluate it at x=1. That gives you m, so you have the slope of the line and the coordinates of a point on the line. Plug those into the point-slope formula for the equation of a line. Set x=0 to find the y-intercept and you'll have b.