# Calculus: Limits

 P: 413 The first part is downright simple. Just put x=0, y=0 in the equation and solve for f(0). For the second and third part.. What does the first principle method of derivative tell you? $$f'(x) = \lim_{h\rightarrow 0} \frac{f(x + h) - f(x)}{h}$$ Using the fact that $f(x + y) = f(x) + f(y) + 2xy$, you have: $$f'(x) = \lim_{h\rightarrow 0} \frac{f(h) + 2xh}{h}$$ Now.. solve this question of limits keeping the first result in mind. Also, you have been given that $$\lim_{h\rightarrow 0} \frac{f(h)}{h} = 7$$. You should be able to do this now easily. Once you have done that, integrate it and then see if you can use the given data to determine the constant of integration. [i'm not so sure if u can determine it.. but do try it]