can someone help me with factorising this equation please

Sep 2012
1
0
United Kingdom
p^2 - 16(q-r)^2 = (p – 4(q - r))(p + 4(q - r))
as x^2 = p^2 and a^2 = 16(q-r)^2
p^2 - 16(q-r)^2 = (p – 4q + 4r)(p + 4q - 4r)