Answer
a) $4$
b) $ y=4x-4$
Work Step by Step
a) Now, $ m_{\tan}=\lim_\limits{ h\to 0} \dfrac{f(x+h)-f(x)}{h}$
or, $=\lim_\limits{ h\to 0} \dfrac{f(2+h)-f(2)}{h}$
or, $=\lim_\limits{ h\to 0} \dfrac{(2+h)^2-(2)^2}{h}$
or, $=\lim_\limits{ h\to 0} (h+4)$
or, $ m_{tan}=4$
b) The equation of a line is: $ y=mx+c $
Now, $ y-4=4(x-2) \implies y=4x-4$
