Given prime numbers p and q where p q, let n=pq and φ(n)=(p-1)(q-1). a) prove that p+q=n-φ(n)+1 p-q = sqrt( (p+q)^2-4n ) b) prove that if p-q is known, then part (a) can be used to factor n. c) Part (b) can be used to factor n when the difference between p and q is not too large, say bounded by a constant k. Describe a method for factoring n when p-q

Question

Given prime numbers p and q where p > q, let n=pq and φ(n)=(p-1)(q-1).
a) prove that 
    p+q=n-φ(n)+1
    p-q = sqrt( (p+q)^2-4n )
b) prove that if p-q is known, then part (a) can be        used to factor n.
c) Part (b) can be used to factor n when the difference between p and q is not too large, say bounded by a constant k. Describe a method for factoring n when p-q<= k, and use this method to factor n=60140021 given that p-q<=10
I have gotten (a) and (b). For part (b), I have 
   p =  (sqrt((p-q)^2+4n) +(p-q))/2
   q =  (sqrt((p-q)^2+4n) -(p-q))/2
for part c, I just dont get it