So the first part of this question is regarding your knowledge and understanding on the subject matter. You should know that for real and equal roots, (b2 - 4ac)=0. (For real and unequal roots, it is >0 and for non-real roots, it is <0.)
Once we know this, we can find the values of a, b and c using the equation. Where a =1, b=(k-5) and c=1.Next, we need to solve for (b2 - 4ac)=0.
(k-5)2- (411) = 0 (k-5)2- 4 = 0
The next step is to expand the brackets:
k2 - 10k +25 - 4 = 0k2 - 10k +21 = 0
Finally, we are left with an equation which can be factored to find the values of k, as follows:
(k-7) (k-3) = 0
Therefore, k = 7 or k =3.