Question 118819
expanding the equation gives x^2-15=2kx-8k ___ x^2-2kx+8k-15=0


for the quadratic to be a "perfect square", (b/2)^2=c ___ so (-2k/2)^2=8k-15


k^2-8k+15=0 ___ (k-5)(k-3)=0