Question

find the value of k such that the line that passes through (0,k) and (-k-1) has a slope of 1/2

Answer 1

Use the point-slope formula:
m = (y-y1)/(x-x1)
Put the values of both the points and the slope and you'll get the value of k :)
UNderstood? :D

Answer 2

\(\begin{array}{ll|ll}
slope = \cfrac{rise}{run} \implies \cfrac{y_2-y_1}{x_2-x_1} \implies \cfrac{1}{2}\\
&(x_1,y_1)&(x_2,y_2)\\
&(0,k)&(-k-1)\\

\end{array}\)