the roots of x^3-6x^2-13x-k=0 form an arethmatic sequence
a) What is the median term of the arethematic sequence
b) Find the value of k
Let the sequence be a-d, a, a+d
So
x3−6x2−13x−k=(x−(a−d))x(x−(a+d))x3−6x2−13x−k=x((x−a)+d))(x−a)−d))x3−6x2−13x−k=x((x−a)2−d2)etc
Simplify it down and equaet coefficients.
+62 
