Factories the expressions-

p²q – pr² – pq + r²

In the given expression

Check weather there is any common factors for all terms;

None;

Regrouping the 1^st 2 terms we have,

p²q – pr² = p[pq – r²] -------eq 1

Regrouping the last 2 terms we have,

– pq + r² = -1[pq – r²] -------eq 2

∵ we have to make common parts in both eq 1 and 2

Combining eq 1 and 2

p²q – pr² – pq + r² = p[pq – r²] -1[pq – r²]

= [pq – r²][p - 1]

Hence the factors of[p²q – pr² – pq + r²] are [pq – r²] and [p - 1]