Question: Factorise:
p2 − 4p − 77
Solution:
The given expression is $p^{2}-4 p-77$.
Find two numbers that follow the conditions given below:
Sum $=-4$
Product $=-77$
Clearly, the numbers are $-11$ and 7 .
$p^{2}-4 p-77=p^{2}-11 p+7 p-77$
$=p(p-11)+7(p-11)$
$=(p-11)(p+7)$
