Consider the following for the next items that follow:

Let $f(x)=\left\{\begin{array}{cc} a x(x+1)+b, & x<1 \\ x-1, & 1 \leq x \leq 2 \end{array}\right.$

If the function f(x) is differentiable at x = 1, then what is the value of (a + b)?

Consider the following for the next items that follow:

Let $f(x)=\left\{\begin{array}{cc} a x(x+1)+b, & x<1 \\ x-1, & 1 \leq x \leq 2 \end{array}\right.$

What is $\displaystyle \lim _{x \rightarrow 0} $ f(x) equal to ?

If f(x) = |ln|x|| where 0 < x < 1, then what is f'(0.5) equal to ?

If f'(x) = cos (In x) and $y=f\left(\frac{2 x-3}{x}\right)$, then what is $\frac{d y}{d x}$ equal to ?