Problem $1$: $(5$ marks$)$ For each of the following functions, find an approximate value for the slope of the tangent line $($by using secant lines$)$ to the specified point $x=a.$ Notice that the tangent includes the point $(a,f(a)),$ use this to find the slope$-$point equation of the tangent line.

$($a$)f(x)=x^2-1,a=2$

$($b$)f(x)=\frac{2x+1}{3x-2},a=1$